Parasite in Love

by Sugaru Miaki


The colorful extravagance of some birds, the deliberately excessive horns, manes, and tusks of some mammals, the complex courting behavior of many animals, the very existence of sex itself - and by extension the love songs on the radio, and all the love-addled poems ever written - all likely evolved because of parasites, because all organisms must run as fast as they can just to stay in place.

- Moises Velasquez-Manoff
"An Epidemic of Absence"

Kengo Kousaka, who joined a small local systems development company after graduating college, decided to quit a year after coming on for reasons that would make anyone raise an eyebrow. From then on, this would repeat in a similar way almost yearly, and in his rolling about between jobs, he suddenly fell into depression. But he had no awareness of his illness; even at the worst of times, when he was so depressed as to find breathing a chore, even when he suddenly found temptations of death crossing his mind, even when he started weeping at night for no apparent reason, he thought it was all the fault of the winter cold.

It happened in winter when he was age 27. It was a bizarre winter, come to think of it. There were a number of meetings, and a number of farewells. There were happy coincidences and unhappy accidents. There were things that changed vastly, and things that didn't change at all.

That winter, he experienced a rather late first love. It was a girl ten years his younger. An unemployed, depressed young man, and a bug-loving school-skipping girl. It wasn't proper in any sense, but it was undeniably love.


"Lifelong copulation?", Kousaka repeated.

"Yes, lifelong," the girl nodded. "Diplozoon nipponicum spend half their lives fused with their partner."

The girl produced a keychain and held it in front of Kousaka.

"This is D. nipponicum."

Kousaka brought his face close and looked it over. Its design was simplified, but it appeared as if it was modeled after a creature with two pairs of wings. The fore and rear wings differed, the fore pair being about three times the size of the rear pair. At a glance, it just looked like a butterfly.

"And despite how beautiful it looks, it's a bona-fide parasite, belonging to Platyhelminthes Monogenea."

"Looks like a plain old butterfly."
"Look closer. No antennae, right?"

Just as the girl said, the creature had no antennae. One could assume they were simply omitted for convenience of design, but the girl considered it an important distinction.

"This actually depicts two D. nipponicum conjoined in an X shape." The girl formed an X with her fingers.

"So since you say they do lifelong copulation," Kousaka said, trying to find the proper expression, "after they conjoin, they're constantly having sex?"

"In a sense, yes. Each one's male sexual parts connect to the other's female sexual parts."
"Each one's...?"

"Yeah. D. nipponicum have both male and female sexual organs. Which they call hermaphroditism. So you might think they could self-fertilize without a partner, but for some reason, they don't do that. They put in the effort to find a partner, then exchange sperm."

Kousaka grinned bitterly. "Talk about luxurious."

"The fact they dare to do with someone else what they could just do alone is kind of loathsome, huh?", the girl agreed. "But there are things to learn from that. For instance, D. nipponicum aren't fussy about partners. As if treating their love at first sight as destiny, they'll combine with the first of their kind they ever meet without any qualms. Also, D. nipponicum don't abandon their partners to the last. Once D. nipponicum join together, they never let go of each other. If you try to tear them apart, they'll die."

"That's why it's lifelong copulation," Kousaka said, impressed. "Amazing. Like a happily-wedded couple."

"Yes. Like birds of a feather, like entwined roots," the girl said proudly, as if one of her relatives was being complimented. "As a bonus, these parasites inhabit koi."


"Yes - so they're parasites of "love." Isn't that such a perfect coincidence? Even further, D. nipponicum who successfully inhabit a koi discard its eyeballs within 24 hours. So the koi, like love, is blind."

"Love is blind," he repeated out loud. "I never expected to hear such a romantic thing out of your mouth."

Hearing this, the girl's eyes widened like she'd come to her senses, and after a pause, she covered her face.

"What's up?"

"...Now that I think about it, maybe sexual organs and copulation and stuff aren't things I should talk about in public so much." The girl's cheeks faintly reddened. "I feel stupid now."

"Nah, it was interesting." Kousaka snorted, finding the girl's flustering funny. "Keep talking. About parasites."

The girl was silent for a while, but slowly began to say more. Kousaka lent her an ear.

Chapter 1: Poisolation

The water from the faucet was piercingly cold. But there was no time to wait around for it to warm up. Kousaka began washing his hands. Immediately, the running water took away all heat in his hands, and they went numb. He stopped the faucet, soaped up his hands and washed thoroughly, then ran the water again. Even after the bubbles were drained away, he kept his hands in the running water. After about two minutes, the water heater finally remembered its duty, and the tap water began to warm up. His frozen hands had a prickling numbness, and couldn't tell hot from cold.

He stopped the faucet and carefully wiped the water with a paper towel. Bringing the numb hands to his face, he closed his eyes and sniffed. Once certain they were odorless, he applied rubbing alcohol from the table all over his hands. Gradually, he started to calm down.

Back in the living room, he threw himself down on the bed. Light weakly shined through a gap in the white curtains; it could have been early morning, or it could have been evening. But either way, time was currently not all that important in this man's life.

He heard a constant stream of children's voices outside. It was the elementary school nearby. Hearing the children playing and having fun would occasionally cause him suffocating sadness. Kousaka turned on the radio by his bed, tuned it to a random frequency, and let music play. An old staticy song covered the shouts of the children.

After quitting his last job, Kousaka made no effort to find a new place of employment, steadily exhausted his savings, and spent his days lying in bed, pretending to think about something. Of course, he wasn't actually thinking about anything. He was just trying to keep up appearances. I'm storing up vitality for the time I'll need it, he told himself. He himself didn't know how to give a "when" to this "time I'll need it."

Once a week, he reluctantly had to go out to do shopping, but the rest of his time was spent in his room. The reason was simple: he had a serious case of germaphobia.

He lived in a small, neat dining-room-plus-kitchen rental apartment within twenty minutes of the nearest train station. It was his one and only holy space. There, he always had two air purifiers running, and there was a faint smell of antiseptic. The floors were so polished as to appear brand new, and his shelves were lined with disposable latex gloves, surgical masks, bacterial spray, wet tissues, etcetera. Most of his clothes and furniture were white or close to it, and his closet was stocked with new shirts still in the bags.

Kousaka washed his hands over a hundred times a day, so they were terribly rough. His nails were neatly cut, with the exception of a long nail on the index finger of his dominant hand. This was his backup measure for when he was driven into situations that called for touching elevator or ATM buttons with his bare hands.

Another part of Kousaka's body that was dubiously "clean" was his hair. He'd let it grow somewhat long. He recognized it was better to have short hair for keeping his room clean, but he really couldn't handle salons and barber shops, so he had a habit of putting off haircuts as much as he could.

While it would be easiest to call him a clean freak, he really had a variety of conditions. If you dig into such people's perceptions of "uncleanliness," you'll discover a number of irrational beliefs. People who call themselves clean freaks in spite of having messy rooms are a superb example.

Kousaka's image of uncleanliness was "other people." More than actual dirtiness, the major issue lay in whether or not another person had some involvement. If it came to having to eat food another person's hand had touched, he'd rather eat something that's been expired for a week.

He saw people other than himself like petri dishes generating bacteria. He felt just the touch of a fingertip would make microorganisms propagate and contaminate his body. Kousaka couldn't hold hands even with someone he was close to - of course, for better or worse, he had no one to hold hands with right now anyway.

Suffice to say, his fastidiousness was a major obstacle in having a social life. Someone who views other people as impurity itself can't form positive relationships. His essential desire not to interact with others manifested in various ways, and irritated those around him. He couldn't put on even an insincere smile, he couldn't remember people's names, he couldn't make eye contact with people... There were too many things to list.

At any rate, dealing with other people was nothing but agony. Back when he was working, everything caused him stress, and all of his desires except sleep vanished.

Above all, company functions like get-togethers and trips were hell itself. After coming home from such events, he would often take four-hour showers, lie in bed, and listen to music to retune his mind. He had to do this to teach himself that there was sound worth hearing in this world, or he'd feel like ripping his ears off. On such nights, he couldn't sleep without music playing.

In short, I'm not suited to be a human, Kousaka thought with some seriousness regarding his fitness for society. As a result, he quickly lost his place regardless of what the job was, and ended up quitting just to get away.

His repeated changing of jobs was essentially a process of eliminating his prospects one by one. In just a few years as a working adult, he felt like he had been thoroughly denied as a human. It was like he was branded with the words "it's no use whatever you do."

It wasn't like he was searching for a bluebird. He knew from the start there was nothing like that out there. It's not as if all people have a calling. In the end, to some extent, everyone has to make a compromise somewhere.

Yet while his head understood this, his heart wouldn't come on board. His mind had been steadily worn down by the day, and his compulsions worsened with it. In correlation to his mind degrading, his surroundings became cleaner, and his room was practically sterilized.


Lying in bed and listening to the music on the radio, Kousaka faintly thought over the events of a few hours ago.

He was at a convenience store. He was wearing disposable latex gloves. These were necessities for him, and especially required in a convenience store or supermarket, riddled with things which he had to touch, yet other people had gotten their sticky hands all over.

He did his shopping with gloves on as usual, but a problem came up midway. As he reached toward a case to grab some mineral water, suddenly, a joint on his right index finger hurt. He looked; the skin had cracked and bled. A common occurrence. He always washed his hands far too much, and this was a dry season, so his hands were as rough as a beautician just starting out.

Unable to bear the feeling of the blood seeping through the glove, he took the right glove off and discarded it. And not liking the unbalanced nature of wearing only one glove, he also discarded the left glove. And he continued shopping.

The person at the register was a girl he commonly saw working part-time here. She was a courteous girl with hair died coffee-brown, and as Kousaka brought his items up, she received him with a full-faced smile. There were no particular problems up to that point, but as Kousaka took the change, the girl handed it to him by wrapping her hands around his.

This was bad.

Kousaka immediately, reflexively shook her hands away. The coins scattered to the floor, and the customers in the store all looked their way.

He looked at his hand, dumbstruck, ignored the girl at the register hastily apologizing, and fled the store without even trying to pick up the change. And after returning to the apartment as quickly as possible, he took a long shower. But he still felt the unpleasant sensation, and rewashed his hands after leaving the shower.

After recalling the whole sequence of events, Kousaka sighed. Even he thought it was unusual. But he simply couldn't stand his bare skin being touched.

In addition, Kousaka was poor with girls who had a sense of femininity, like the one at the register. It wasn't limited to women; he similarly disliked men who pushed their manliness to the forefront. He felt a similar sense of impurity from both of them. It sounds like something a girl entering puberty would say, but it really felt that way to him.

During childhood, he thought his phobia would naturally be cured as he grew up, but in reality, it only got worse. At this rate I'll never marry, to say nothing of making friends, he muttered to himself.


When Kousaka was nine, he had a mother. Just before he turned ten, she left this world. It was judged an accident, but Kousaka still suspected it to be a suicide.

She was a beautiful woman. Cultured and resourceful, with good taste in music and movies. Apparently she was an Electone instructor before she met Kousaka's father. It was a relatively small class, but reputable, and quite a few students came from far away to take it.

It still baffled Kousaka why a perfect woman like her chose a mediocre man like his father as a partner. His father was not a classy man, to say the least. His face was like a failed montage of parts that didn't fit together, he didn't earn much, he had no hobbies but also no passion for work, and generally, you couldn't find any merits worth calling merits (though to the Kousaka of today, just living normally and keeping a house was worthy of respect).

Kousaka's mother was harsh on herself, and sought similar effort from her son as well. From a time before Kousaka can remember, he was forced to take various lessons, and when at home, followed a minute-to-minute schedule devised by his mother. Being so young, he thought all mothers were like this, so he harbored no doubts and obediently did as told. If he defied her, he might be locked out of the house barefoot or not get any meals all day, so he had no choice.

The fact that he didn't live up to even half of her expectations seemed to make Kousaka's mother more bewildered than upset. Why is this child, my own flesh and blood, not as perfect as me? Perhaps there was a problem in how I raised him?

Strangely, she doubted everything except Kousaka's disposition. Yet that most likely wasn't a result of partiality as a parent, but a manifestation of her warped self-love. She chose to doubt her teaching methods before she'd doubt her own blood, that's all.

Like many perfectionists, Kousaka's mother liked cleanliness. When Kousaka's room was messy or he came home looking dirty, she had a deeply sorrowful look. That was much more harsh on him than shouting or hitting. On the other hand, when Kousaka went and cleaned his room or washed his hands, she always praised him. As someone without any particular scholarly or athletic skill, these were one of few opportunities to make his mother happy. He naturally came to like cleanliness more than other children his age - within reason, however.

Abnormalities began at age 9, at the end of summer. One day, Kousaka's mother started being very kind to him, like a changed person. As if regretting her prior behavior, she discarded all the rules she'd imposed on him, and treated him very affectionately.

Freed from all his limitations and able to experience an unrestricted, childlike life for the first time, Kousaka didn't give any deep thought to the sudden change in his mother's attitude.

Occasionally, she would gently put her hand on Kousaka's head and stroke it, repeating "I'm sorry." He wanted to ask what she was apologizing for, but felt it might upset her if he did, so he stayed silent and let his head be stroked.

He would realize afterward: She wasn't apologizing for something she had done, but something she was about to do.

After just a month of acting as a kind mother, she died. While driving home from a shopping trip, she had a head-on collision with a car going far faster than the speed limit.

Naturally, it was considered an accident. But Kousaka knew something: at certain times of day, that road became an ideal place for committing suicide. And it was none other than his mother who'd told him that.

After the funeral, something in Kousaka changed. That night, he washed his hands for hours. His right hand with which he'd touched his mother's body felt unbearably disgusting.

When Kousaka woke up from a light sleep the next morning, his world had changed. He sprang out of bed and ran into the bathroom. And he took a shower lasting hours. Everything in the world seemed to be dirty. Hair in the drain, mold on the walls, dust on the windowsill - just looking at these things made a chill go down his spine.

And in this way, he became a clean freak.

Kousaka himself saw no direct cause and effect between his mother's death and his fastidiousness. It was nothing more than one impetus. Even if it weren't for that particular incident, surely something else would have awakened this. It's just something that's always been in me.


Chapter 2: Computer Worm

It's difficult to explain the eeriness of an intercom echoing in the dead of night to someone who's never experienced it.

You're relaxing, defenseless, in a completely silent room. Suddenly, the silence is broken by an inorganic sound notifying you of a visitor. For a moment, your thoughts halt. You check the clock, and indeed, it's clearly no time for a person to be visiting. Your head fills with questions and doubts. Who? Why now? For what purpose? Did I lock the door? What about the chain lock?

You hold in your breath, listening for the person beyond the door to enter. How much time has passed? It could be seconds, it could be minutes. You timidly go to the front door and look through the peephole, and a mysterious stranger appears and leaves without leaving any hints. It ends with everything still up the air, and the echo of that ill-omened electronic noise continues for the rest of the night...

It was a visit without any forewarning.

At the time the intercom rang out, Kousaka was cleaning his computer keyboard. The PFU-made keyboard had no markings on the tops of the keys, and not from being rubbed away by repeated cleaning, but because it was designed that way. He'd taken out and washed all the keys just last week, but he just had to do a thorough cleaning after every use.

A table clock showed it as past 11 PM. Before he could even think about who it might be at this hour, Kousaka's smartphone, which had been charging on the desk, vibrated. He intuitively realized that the corresponding timing of the intercom and the email was not a coincidence.

He picked up the smartphone and checked the new email.

Open the door. I have no intention of hurting you.
I want to talk about viruses.

He looked up and glanced in the direction of the front door. His apartment wasn't equipped with orthodox systems, and it was easy for intruders to enter the building without being tenants. The person who sent the text was likely already standing outside the room - at nearly the same time he realized this, there was a knock on the door. It wasn't a rough knock, but a kind of knock that was for letting your presence be known.

Kousaka stared at the phone in his hand, wondering if he should call the police. But the message displayed there gave him pause.

"I want to talk about viruses."

He definitely had some idea about what that message could mean.

Kousaka first acquired an interest in malware three months ago, in the close of summer 2011. One day, he received a text from an unfamiliar address on his phone.

"The world will be ending very soon."

An ominous message. But at the time, as he was feeling uncomfortable with what was now his fourth job and disheartened, the message was somewhat refreshing.

Kousaka closed his eyes, and briefly enjoyed a vision of the world ending. The sky turned red, sirens wailed through town, unhappy news played on the radio. He imagined the scene at length.

It may sound absurd, but Kousaka was saved by that imprudent message. A baseless consolation, effectively a lie, was just what he needed at the time.

When he looked it up later, he found the message was forcibly sent from a device infected with malware called "Smspacem." Malware is a programming term referring to malicious software or programs that cause computers to behave irregularly. Most people refer to all such things as "computer viruses," but technically, a virus is no more than a sub-category of malware.

To describe Smspacem briefly, it's "malware that informs people the world is ending." Infected devices, on the date 5/12/2011, were made to send a message about the world ending to all addresses on their contact list.

According to security reports, Smspacem was malware that targeted users in North America. So the fact that a similar message in Japanese was sent to Japan-dwelling Kousaka in late September meant there was probably some curious sort who made a Japanese-centric variant of Smspacem.

Once, while lazily lying in bed after quitting his job, Kousaka suddenly recalled Smspacem. And he thought: I wonder if I could make something like that myself? I wonder if I could reproduce, in a different form, that sensation of a little seam forming in my ordinary life?

Luckily, he had plenty of time. So Kousaka picked up the knowledge needed to create malware. He had a base of knowledge and experience from working as a programmer, so in just a month after he began studying, he completed some original malware that didn't depend on any toolkits.

I think I'm suited for this field, Kousaka thought. He had a talent for finding the best algorithm for a problem without anyone teaching it to him. A rare example of born punctuality and perfectionism working in a positive way.

Before long, the malware he created began to appear in security reports by major software corporations. This spurred Kousaka to begin the creation of new malware. At some point, creating malware became the one thing he lived for.

An ironic turn of events. A person who on one hand was so scared of viruses and insects in the real world that he found it hard to live, meanwhile found something to live for in creating viruses and worms in the virtual world.

As he faced his computer and typed on his keyboard, Kousaka sometimes thought: Maybe I'm convinced my genes won't be left behind in this world, which is why I'm spreading self-replicating malware across the internet instead.

There are actually various things which are considered malware. Traditionally, malware is divided into three categories: viruses, worms, and trojans. But over the years, malware has gotten more complex, and with the appearance of malware that doesn't fit into the traditional categories comes new definitions like backdoor, root kit, dropper, spyware, adware, and ransomware.

The simple three categories of malware - virus, worm, and trojan - are relatively easy to understand the differences between. First of all, viruses and worms both have self-infecting and self-multiplying abilities, but viruses must inhabit other programs to exist, whereas worms can exist independently without a host. Trojans are distinguished from viruses and worms by a lack of self-infecting and self-multiplying.

The Smspacem that got Kousaka interested in malware would be defined as a worm. It collects email addresses from an infected computer, sends out many emails with copies of an illegal program attached, and repeats the process with those infected to spread further - this is known as a mass mailing worm.

This was, naturally, the kind of malware Kousaka developed as well. He gave the mass mailing worm he was working on the codename "SilentNight."

SilentNight was a worm that attacked on a set date. Starting up on 5 PM on December 24th, it disabled transmission functions on infected devices for 2 days. To be more exact, it ended all transmissions as soon as they began. As a result, the owner of the infected device would be temporarily deprived of not only phone calls, but emails, texts, online call services - any means of communication.

The codename SilentNight, then, was a play on how it was both a virus that activated on Christmas Eve, and one that took away communication from friends or loved ones, forcing them to spend a quiet Christmas night alone.

At the end of November, SilentNight was completed at last. Kousaka spread the mobile worm across the network. Depending on how you think of it, this could be called the beginning of everything. It was only a few days later that he realized what a fateful downward current he was stepping into.

The intercom sounded again. Kousaka stood up from his work chair. He felt like he might regret it if he pretended to be out. If he didn't clear up the visitor's identity and purpose here and now, he'd no doubt be tormented by an unfathomable unease in the weeks to come. And at any rate, they already knew his address and email, so it would be futile to hide.

The door camera was broken, so he'd need to look through the peephole to see his visitor's face. He cautiously left the living room and stood at the front door. Peeping through, he saw a man wearing a coat over a dark suit. Seeing the outfit, Kousaka's wariness lessened slightly. Certain suits and uniforms have a power of putting people at ease unconditionally.

After checking that the chain lock was on, he opened the door. As if anticipating that he'd be received from behind the chain lock, the man had moved to a position opposite the crack in the door.

The man was a good few inches taller than Kousaka. Kousaka was 5'8", which meant this man was 6' or more. He also had a solid physique. The Chester coat he wore over his suit may have originally been black, but appeared gray from dirtiness. His eyes had deep bags, and his jaw was covered with an unkempt beard, with white hairs mixed among oily ones. He had a friendly-looking smile, but his eyes seemed hollow.

"Hey," the man said. His voice was low and hoarse, but strong.

"Who would you be?", Kousaka asked over the chain. "What do you want at this hour?"

"Just like the email said. I want to talk about viruses."

Kousaka gulped. "Did you send that email?"

"Right," the man affirmed. "Can I come in? You don't want to be asked about it either, do you?"

Kousaka reached for the chain, then hesitated. True, like he said, he didn't want to be asked about it. But there was no guarantee that it was safe to let him in. From his clothes and vibe, Kousaka instinctively supposed that the man before him, if he was so inclined, could twist his arm with no difficulty. That he was used to such actions, and preferred easily-understood body language to annoying communication. He was ready to respond violently at any moment depending on my actions.

"You seem wary," the man said, seeing Kousaka's unease. "Well, maybe it'll be easier to talk that way rather than trying to relax. I don't intend to act in a rough way, but I guess you won't believe that from my mouth."

Kousaka's focus instantly turned to the room. And once more, the man saw right through him via his minor actions.

"Relax, I know about your cleanliness. I won't come past the entryway."

Kousaka was speechless, and his lip quivered.

"...You know that much?"
"Yeah. Now won't you let me in already? I'm freezing out here."

Kousaka hesitated, but finally gave up and carefully released the chain lock. True to his word, the man didn't set foot beyond the entryway, closed the door behind him, leaned on it, and sighed. He started to take a cigarette out of his pocket, but noticed Kousaka watching and put it away.

"It's not just you, really... Lots of young people these days like to be clean," the man said as if to himself. "I guess it figures since they're selling a product, but if you just look at commercials, it feels like everything is dirty. Sofas and mattresses are full of ticks, cutting boards and sponges are full of bacteria, smartphones and keyboards get dirty with use, your mouth after waking up smells worse than a steaming pile..." As he spoke, he took a lighter from his pocket and flicked it. "But since all that stuff surrounds us, I guess that means we've always been fine with it? Then isn't there nothing to worry about? I guess it's just what companies do. People make up problems that don't even exist."

Kousaka pressed him to get to the point. "...What did you want to talk about?"

"I'm here to threaten you," the man replied just as directly. "Kengo Kousaka, what you're doing is a clear criminal act. If you don't want to be prosecuted, you'll listen to what I say."

Kousaka kept silent. It was so sudden that he couldn't quite keep up, but he supposed this man had determined by some means that he was the author of the malware, and was here to threaten him over it.

If the man knew everything about the situation, there was nothing Kousaka could do. However, Kousaka considered, until it was clear how much he did and didn't know, he couldn't carelessly open his mouth more than necessary. It wasn't impossible that this man actually knew almost nothing about the malware, and was bluffing to try and extract information. There was still room for bargaining, perhaps.

"Your face is saying "how much does this guy know?"", the man said.

Kousaka kept his silence.

"I see." The man's expression changed slightly. Maybe it was a smile, maybe it was showing discontent. "To tell the truth, I don't possess full knowledge of everything. For instance, why the virus's activation date had to be Christmas Eve. Why someone with this much programming expertise hasn't kept a job and is absorbed in making viruses. I could go on and on with points that seem unclear."

In short, the man was saying "I know everything."

"...I thought I'd discreetly covered my tracks to not leave any evidence," Kousaka said with resignation. "I'm just asking out of pure curiosity, but how in the world did you determine the author of malware that hasn't caused any damage yet?"

"No obligation to tell you that."

He's right about that, Kousaka thought. No one would purposefully show their hand in this situation.

"But," the man continued, "I'll tell you just for the sake of your puny pride. It's true, you're a pretty tough customer in the virtual world. I'll admit that much. But on the other hand, you're totally defenseless in the real world. ...You should get what I'm saying from that alone, right?"

Something cold ran down Kousaka's spine. Thinking about it, for the past few months, he left at a set time and weekday every week to go shopping, and during that time, the house was left empty. And when the weather was good, he kept the curtains open all day (he had a powerful belief in the bacteria-killing effect of sunlight). So if someone felt like it, it wasn't impossible to peer into his personal life - to be concrete, someone could sneak into his room, or peek through a telescope.

"And to answer your earlier question," the man appended, "I didn't start my investigation convinced you were a cybercriminal. I was just gathering information to determine whether or not Kengo Kousaka was suitable. Since I found blackmail, I decided to shift to using that, but originally I intended to just hire you for money."

"Suitable? For what?"
"For what I'm here to talk about."

A silence fell between the two. The man seemed to be waiting for Kousaka to speak.

"...So what is it you came to threaten me to do?", Kousaka asked, half in desperation. "I don't think I can do much..."

"I'd appreciate if you made it quick. If you'll keep being honest like that, then I won't have to threaten you any more than necessary."

After a breath-long pause, the man broke the subject.

"Kengo Kousaka, I want you to look after a certain kid."

"A kid?"

"Yes, a kid," he repeated.


I don't have too much hope for you, the man said as he left. Can't really blame him, Kousaka thought. Because this job really was a heavy burden for him. He disliked interacting with other people as it was, but he was especially bad with children and old people. The reason, of course, being "they seemed dirty."

But that said, he couldn't just give up from the get-go. If he couldn't fulfill this request, Kousaka wouldn't just be unemployed, he'd be unemployed with a criminal record.

Apparently, the kid's name was Hijiri Sanagi. Kousaka wasn't given any information beyond that.

His blackmailer also gave his own name: Izumi. Izumi's instructions were simple.

"At 5 PM tomorrow, go to Mizushina Park. Near the park, there'll be a kid feeding swans. That's Hijiri Sanagi."

Kousaka didn't quite understand the situation, but nodded for the time being.

"Your first duty is to become Hijiri Sanagi's friend."

Then Izumi appended a brief explanation of what the payment for success would be. The amount he specified was pretty big money to Kousaka at the moment.

Once Izumi left, Kousaka went around his room cleaning like mad. Just thinking about the possibility that someone had been intruding in there while he was out made him feel like he was losing his mind. But as much antiseptic as he used, the thick sense of an "other" wouldn't seem to go away.

The next night, Kousaka wore a coat, donned latex gloves on both hands, put on a disposable face mask, and placed disinfecting sheets and spray in his bag. Carefully checking the lock, he opened the door with a feeling of hopelessness.

It had been a long time since he'd left his holy ground past sunset. The air outside was piercingly cold, and his face and ears stung.

He chose to wear a suit so as not to make Hijiri Sanagi wary. Most people would be, if a stranger talked to them out of the blue. Even moreso at night. At times like these, a suit could give people a sense of relief. Kousaka was given this thought by taking into account his own experience last night.

He came to a stop on a sidewalk outside the train station. A small crowd had formed on the side of the road.

Peeking over their shoulders, he saw the onlookers were circled around a street performer. The performer was a man in his thirties, with a suitcase in front of him serving as a pedestal, on which marionettes danced. The man was making full use of all his fingers to control two marionettes at once. He's dexterous, Kousaka admired. A nearby cassette player played background music, "The Lonely Goatherd."

Kousaka watched the performance for a while. The marionettes had highly deformed designs, their facial features all different sizes, which took it past comical to grotesque. It seemed the male marionette chased the female marionette, or maybe the female marionette chased the male marionette, and as the two awkwardly kissed at the end, the music ended, and there was a round of applause.

With the audience feeling good, the puppeteer began to skillfully ask for payment. Once the other viewers left, Kousaka put a 1000-yen bill in the suitcase. The performer grinned, and said in a whisper:

May you have the puppets' protection.

Kousaka resumed walking. Luckily, the designated park was only a 30-minute walk from his apartment, so there was no need to use public transportation.

Kousaka had imagined, albeit faintly, that Hijiri Sanagi was a boy around ten years old. Just the look of the name, "Hijiri Sanagi" - and this was purely from Kousaka's assumption of how the name was written in kanji - seemed more masculine than not, and "sanagi" was the word for "chrysalis," which in his mind had more of an association with boys.

So it wasn't unreasonable that when he arrived at Mizushina Park and found the person in question, he was confused.

He first noticed the hair, dyed silver. It was short, platinum-blonde hair that could look ash-gray depending on the lighting, and her eyebrows were also slightly bleached. In addition, her skin was unhealthily pale, and her eyes were a stark black that sucked you in.

His gaze next went to the long legs coming out of her skirt. Despite the temperature being enough for breaths to turn white, she wore a short skirt that left her thighs exposed. She wore no tights or stockings, either. If Kousaka remembered correctly, she was wearing the girls' uniform from a high school in the area. She had a tartan scarf and an off-white cardigan on, but one couldn't imagine that these covered for how cold her legs must have been.

She was wearing thick monitor headphones like would be used in a studio. With their bland design, there was not even a chance of them being meant as a fashion statement. From the sound that seeped out, Kousaka supposed she was listening to old rock music.

Kousaka's gaze finally landed on the cigarette between her thin lips. At first, he couldn't tell whether or not they were frigid white breaths, but closer inspection revealed it was indeed smoke coming out of her mouth.

Hijiri Sanagi was a girl around seventeen years old. And not just any girl, but a type of girl Kousaka really couldn't deal with.

Sheesh, what was that Izumi expecting from me? Kousaka twisted his neck. What could have led him to the conclusion that I'd be suitable for this? He didn't even have a clue.

He just wanted to run, but that wouldn't fly. If he gave up his task already, Izumi might turn him in to the police any moment. While he did feel that wouldn't be entirely undeserved, he could at least try and fail first, and it wouldn't be too late to give up then.

No need to get nervous. It's not like I was told to seduce her and make her my lover. Just being friends will be enough.

He took off his face mask and put it in his pocket. Determined, he approached Sanagi.

Like Izumi said, Sanagi was standing near the lake and feeding swans. She took bread crusts out of a paper bag and threw them into the air, and the swans swarmed them all at once. She watched contentedly. She didn't seem to notice Kousaka beside her.

Not wanting to surprise her, he slowly entered her field of view and spoke.


After a few seconds, Sanagi looked toward him.

Facing her head-on, Kousaka couldn't help but admire Sanagi's appearance. Her figure made him imagine a female android created according to some clear design. Said design, however, wasn't meant to relax or soothe people, but to disturb and tense up anyone nearby.

"...What?", Sanagi asked, taking off her headphones and looking at him suspiciously.

Kousaka inadvertently looked away. It seemed his suit wasn't doing its job of easing her wariness. That figured. A schoolgirl in uniform being approached in the park at night by a young man in a suit was unnatural, no question. To put it lightly, it felt dangerous. Exercise clothes might have seemed more natural, at this rate.

"Can we talk for a second?", Kousaka asked, putting all his energy into a friendly smile. "Do you have time right now?"

"No," Sanagi replied lazily, cigarette in mouth. "I'm busy."

The natural response. Sanagi put her headphones back on and returned to her own world.

At this point, there was nothing Kousaka could do. The problem was something even more fundamental than the age gap or gender difference: he had never once endeavored to be friendly to another person.

Kousaka was at a loss. He couldn't think of his next move, so he followed Sanagi's example and watched the swans chase food from a fair distance away.

He disliked the majority of wild animals, but swans were one of few exceptions. Their bodies were all white, for one, but most importantly, they only appeared in winter. The way they always soaked in chilly water had a clean feeling to it. It was strictly his imagination, however, as this was actually because of pathogens in their bodies.

He took another look around the park. The lamps illuminating the snow-covered park made it seem like the whole place had a faint pale glow. Listening closely, he heard not only swans, but snow falling from branches to the ground. He closed his eyes and focused on such sounds.

He heard a sigh. Sanagi took her headphones off again and looked his way. Kousaka's eyes wandered from the piercingly sharp gaze. For a moment, he saw a blue earring glinting on Sanagi's ear.

"Hey, what do you want with me?"

This was no time to carefully consider words. I have to say something and make her less wary, Kousaka thought, and so he opened his mouth.

"I want to be friends with you."

It struck him as shady once he'd said it. Just the kind of line someone approaching with impure motives would say. Wasn't there some better way of expressing it? He could hardly make a case if she went running to the police to say "a suspicious man called out to me."

Sanagi looked at Kousaka with emotionless eyes. There was a long silence. She sucked on her cigarette and dropped the ash with an experienced motion. Then she kept staring at Kousaka as if appraising him.

Just say something already, anything, Kousaka pleaded silently. The cold sweat under his arms was unpleasant. He wanted to give up on this idiocy, go back to the apartment, and take a shower. He longed for his sacred grounds full of air purifiers and antiseptic.

After a while, Sanagi discarded her now-short cigarette by her feet. The flame went out immediately as it touched the ground wet from the snow.

"I guess Izumi asked you, right?", Sanagi asked listlessly, letting out a final puff of smoke. "You're the seventh one so far."

The smoke Sanagi let out was carried on the wind, and Kousaka covered his mouth at once.

Then a moment later, he guessed the meaning of "the seventh one."

"...You mean there have been others before me he's asked to be friendly with you?", Kousaka asked.

"Huh, Izumi didn't tell you anything?"

Kousaka revealed everything with resignation. "He just told me to "look after a kid." I assumed you were like a ten-year-old boy, so I was confused when I saw you."

"Then we're in the same boat. I never imagined he'd send a guy as old as you over. Wonder what he's thinking?" Sanagi scratched her chin with annoyance. "What's your name?"

"Kengo Kousaka."

"Izumi threatened you into doing what he says too, didn't he? Hey, what weakness is he exploiting from you?"

He hesitated briefly, but decided to answer honestly. Even if he kept his silence here, Sanagi would just get it out of Izumi.

"He's letting some criminal behavior of mine slide."

Sanagi showed great interest in those two words. "Criminal behavior?"

"Cybercrime. I made a computer virus and spread it."
"Why'd you do that?"
"Because I like to. It's a hobby."

"Hmph. A hobby." Sanagi furrowed her brow, finding it hard to understand.

"By the way, what's your relation with that man?"
"I dunno. Parent and child?"

"Parent and child," Kousaka repeated. "I don't mean to stick my nose in someone's family matters, but were you ever taught to show respect to your parents at your house?"

"It might be parent-in-law and child."
"...Well, you don't have to answer if you don't want."

Kousaka turned around, putting his back to a fence, and looked up at the night sky. Just then, he discovered what looked like a bird's nest in the branches up above him. But it was too well-formed for a bird's nest, and a little too big. Maybe it's mistletoe, he concluded. He'd heard there were parasitic organisms that inhabited cherry trees and the like and stole nutrients.

Sanagi seemed to remember something and spoke up.

"Oh yeah, did Izumi say he'd pay you?"
Kousaka nodded. "If this job went well, sure."
"How much?"

Kousaka quietly informed her of the amount.

"That's quite a bit."
"Yeah. It's a small fortune to me right now."

Then Sanagi extended a hand toward Kousaka.

The sight of her throwing bread crumbs barehanded crossed his mind, and he stepped back without thinking.

However, she wasn't seeking a handshake.

"Give me half," Sanagi casually demanded. "Then I'll be your friend."

"...Is that what friends say?"

"A man like you and a girl like me becoming friends needs that kind of value. Common sense, right?"

"Is that how it is...?"

"That it is," Sanagi stated confidently. "If you don't want to, I don't mind. I don't care what you do."

"Got it. I'll pay." Kousaka readily accepted the demands of the girl years younger than him. Then he asked, taking a look around: "...By the way, you won't let Izumi hear about this part, will you?"

"Yeah, it's fine."

"How can you say that for sure?"

"By having years of experience," she answered. "Now, hand over the money quick."

"...Can't it wait until after I get my payment?"
"No. If you can't pay upfront, I can't trust you."

"I don't have much on hand. Can you wait until next time we meet?"
"Sure, but don't try to fool me. If you offend me, I'll go to the police and tell them everything that did and didn't happen."

"I'm not lying. I'll have it ready by next time."
"Then I'll come see you tomorrow. Tell me your address."

Kousaka winced. What a forceful girl. He told Sanagi the apartment address, and she entered it into her smartphone. It seemed she was checking the location with a map application.

"It's in walking distance from here," Sanagi said to herself. "When do you get home?"

"Anytime... so, what's your job?"
"Then why are you wearing a suit?"

He didn't care to explain, so Kousaka just replied "For show."

Sanagi had an expression of deep shock, but immediately muttered "Well, I guess I can't speak ill of others" and glanced toward her own outfit. Kousaka waited for further words, but she'd already wrapped things up for herself.

"You know, I was wanting somewhere to kill time all day. Loitering around outside on weekdays would get me escorted home."

"You don't go to school?"

Sanagi ignored that question. Kousaka figured it was a pointless question, too. A proper student who attended class wouldn't have hair dyed this color or earrings.

"I'll come visit at whatever time tomorrow. Bye-bye."

With that, Sanagi put her headphones back on, turned her back to Kousaka, and began to walk. He hastily cried "Hold on," but his voice was overpowered by the music.

This has gotten worrying, Kousaka thought.

His holy ground was in danger.


Chapter 3: The Lady Who Loved Insects

Kousaka first got a girlfriend in autumn when he was 19. He was introduced to a girl two years his elder by a not-particularly-friendly high school acquaintance, and by going with the flow, they started dating. Her appearance, personality, hobbies, skills, you name it, were completely average. He couldn't even remember her face very well now. All that was left in his memories was that she had short hair, and her face dimpled when she smiled.

Before they started their acquaintance, Kousaka decided to be frank about his cleaning habits. He explained that it was serious enough to impede regular life, but she just smiled and accepted it.

"That's okay. I'm kind of a clean freak myself, so I'm sure we'll get along."

It wasn't a lie, really. She was rather clean-loving. She always carried around various anti-bacteria products, washed her hands frequently, and took one or two - on days off, three - showers a day.

But compared to Kousaka, she really was nothing more than "clean-loving." It was just a strong attention to hygiene, and decisively different from the compulsions he had.

Her theory was that even the most fastidious person could get over most obstacles as long as they had trust. Kousaka insisted that no matter how much they might trust each other, if he "can't," he can't - but she rebutted that this simply meant there wasn't enough trust. She viewed the fact that as much as time passed, he wouldn't kiss her, much less hold hands, as proof of insufficient love. While it was true there was a lack of love, she wouldn't lend an ear as he tried to make her understand the more fundamental problem.

Their semi-similar personalities made for calamity. She was convinced she understood fastidiousness, and had a kind of pride in her own love of cleanliness. The actions of Kousaka's that went beyond her understanding - washing change after getting home, discarding pens he lent to others, taking a day off class just because of a light drizzle - she decided for herself that these arose not from a fear of the unclean, but a different mental cause.

She wasn't a bad person, but she had a fatal lack of imagination. It was a miracle their relationship even lasted three months. After breaking up with her, he didn't find anyone new. His first and last lover. Well, then again, maybe there wasn't any love there at all.

Hijiri Sanagi visited the room at 2 PM. The intercom sounded, followed by a sound like the door was being kicked down. He unlocked the door and opened it to find Sanagi standing there with her hands in her cardigan's pockets, pursing her lips with displeasure.

"You should leave it unlocked. You want the others to see me come in?"

"My bad," Kousaka apologized.

"I assume you've got the money?"

He handed Sanagi an envelope, and she opened it and checked it on the spot. Once certain the specified amount was inside, she put it back and placed it in her bag.

"As promised, I'll be your friend." Sanagi grinned. "Let's get along."

"Yes, let's," Kousaka politely replied. "That aside, before you come in the room, there's one thing I want to ask..."

He was going to ask her to wait so he could get wet wipes to at least clean her exposed skin with, but it was too late. She threw off her loafers, ignored the slippers Kousaka prepared for her, went into the living room, and sat down on the bed like it was her own. Kousaka nearly shrieked.

"Wait, please, not the bed, okay?", Kousaka begged, pointing to his work chair. "If you're going to sit, use that."

"Don't wanna."

Kousaka's pleas were in vain, and Sanagi lay face-down on the bed, put a pillow under her chin, and began to read a book from her bag. Kousaka cradled his head. This is the worst. He'd have to wash those sheets and the pillow cover once she left.

"Incidentally, how long do you plan on staying here?"
"About two hours," Sanagi answered without looking up from her book.

"Err... and what should I do during that time?"
"Don't ask me. Make a computer virus or something?"

Then Sanagi put on headphones and started listening to music. She had no intent whatsoever of striking up communication with Kousaka.

Kousaka sat in the work chair, turned away from the bed, and opened a book he'd been reading. He wasn't in the mood for reading, but he didn't know what else to do. A few pages in, he heard the sound of a lighter clicking behind him. He turned around to see Sanagi trying to light a cigarette.

"No cigarettes," he warned, standing up in a hurry to speak into her ear. "Please, just endure it while you're in this room."


Sanagi reluctantly shut the lighter and put the cigarette in her mouth back in the case. Kousaka sighed with relief. Still, what a thing to do to put back a cigarette she'd already put in her mouth. Didn't she find that filthy? Well, surely someone with such hygiene attitudes wouldn't smoke in the first place.

After being informed of the no-smoking rules, Sanagi obediently read on the bed. Kousaka wondered what kind of book she was reading and tried to look, but the writing was too small to tell, and a leather cover obscured the front of the book.

Kousaka opened his book again. But he couldn't focus on the words, and staring at the blank space on the page, began to think about things unrelated to the book's contents.

Ultimately, what did that Izumi person hire me for? What kind of role was he expecting me to fill for Sanagi? Izumi was saying he "wanted me to look after a kid." And then said to "be friends with Hijiri Sanagi." And it seemed she didn't diligently attend school much at all. From all of these, maybe it was proper to assume that my intended role was "someone who, as a friend, can help the school-skipping Hijiri Sanagi return to school."

But then, Izumi's use of the word "suitable" made me wonder. I can't imagine I'd be considered "suitable" if what you want is someone who can guide a delinquent student. Though granted, I might be a superb bad example.

Or maybe I should look at it more simply than that. Maybe Hijiri Sanagi's parents indulge her, silently consenting to her skipping school, but are hiring people to be friends so she doesn't get bored. In that case, the "suitability" would mean being friends who are unsuited to society like her. Surprisingly, this felt closest to the truth.

But in any event, putting an underage girl in the care of a 27-year-old man was certainly not proper. Did Izumi or Sanagi's parents understand that she was in my room?, Kousaka wondered. Perhaps Izumi chose me to be a friend because he knew my cleanliness guaranteed he wouldn't even touch a woman? If so, his judgement was extremely apt. I couldn't lay a finger on Hijiri Sanagi even if I was asked to. Maybe that could be considered suitability, too.

After about an hour, Sanagi took off her headphones, and Kousaka asked a question, having waited for her to do so.

"Hey, Hijiri-chan, what role do you think Izumi wants me to fill?"

"Who knows. Maybe he thinks you could help me rehabilitate?", Sanagi said, turning over on the bed. "Also, don't ever say "Hijiri-chan." It's gross."

"I was asked to look after you, but what exactly should I do for that?"

"Don't do anything," Sanagi spat coldly. "It's best to just keep fooling Izumi's eyes like this and wait until he gives up. Don't think I'm seriously going to try and be friends. It's impossible anyway."

"...Understood," Kousaka nodded. That seemed safest, like she said.

"Oh, but," she appended. "I guess I will trade contact info with you. If I don't, Izumi will find it unnatural."

Sanagi held out her smartphone. Kousaka took it, face twitching.

"Add yourself."

Kousaka followed the instruction and registered his number on her phone. He faintly expected it, but there were only three people in her address book. And those three numbers didn't even have names assigned to them, to boot. She didn't seem like the most sociable sort.

Once done, Kousaka quietly washed his hands with disinfectant. Who knows what's on other people's belongings. Especially things they use daily.

Once two hours had passed, Sanagi closed her book, put it in her bag, and left the room. Kousaka put the the sheets in the washing machine and went around cleaning everything, then showered for about an hour.

Sanagi had said "I'll come around 6 PM tomorrow." This is no joke, Kousaka grieved. At this rate, his holy grounds would be completely dirtied. Wasn't there some way to prevent contamination? His ideal would have been for Sanagi to take a quick shower and change into clean clothes before entering the living room, but it would unquestionably just annoy her to make such a request. Besides, it may have just caused unwanted misunderstandings.

In the end, he came up with no good ideas. The next day, and the day after, Sanagi spread filth around his room. She might have not had any ill intentions, but as a result, Kousaka became neurotic about it and couldn't sleep at night. His room was losing its function as a holy ground. Sanagi always lay in the middle of the bed, so he started sleeping in the corners. He nearly fell to the floor many times while getting accustomed to it, but eventually learned how to properly position himself.

Maybe if he just said the words "I'm a clean freak," Sanagi might have shown a little consideration. However, since breaking up with his girlfriend, Kousaka had never revealed it to anyone. Not only that, he took great efforts to not do anything compulsive where people were watching. His efforts were successful enough that at some of his workplaces, there were people who didn't realize he had any such disorder. They merely thought of him as a person who was often late to work and bad at socializing.

"If my being a clean freak was common knowledge, then maybe I would have some small relief from my difficulties" - such thoughts never crossed his mind. But it wasn't like it was selective obstinacy. People with obsessive-compulsive disorders always try to keep such thoughts and actions hidden from others.

Being aware of your own abnormality is a feature of this disorder. Those who have it don't try to "make others understand." Because they acknowledge they won't be able to have people's understanding. But despite having that level of objectivity toward themselves, that doesn't mean they can stop their compulsions. Rational arguments are all but meaningless. Pharmacotherapy using SSRIs and exposure response prevention therapy are said to be effective treatments, but Kousaka tried them during college, and it only seemed to make things worse.

It was questionable whether Sanagi noticed his disorder or not. Sometimes she would smell the antiseptic scent and complain "Smells like an infirmary," but that was all.

Belying her appearance of silver hair and earrings, Hijiri Sanagi was a bookworm. She might not have had any interest in novels and poems, though, as she read nothing but technical books and science magazines. Once, she fell asleep with her book open, so Kousaka was able to sneak a peek inside. The book she was reading then was about parasitic diseases.

He later had more chances to peek at what she was reading, and found that 90% of the books Sanagi read were about parasites. It appeared she had an unparalleled interest in them.

Kousaka recalled a story from the Tsutsumi Chunagon Monogatari he'd studied in high school, The Lady Who Loved Insects. It was about a strange noble girl who was blessed with beauty, yet did not use cosmetics nor blacken her teeth, but just stared at caterpillars. It seemed a fitting nickname for this girl who was treated by Izumi overbearingly like a princess, and read nothing but books about parasites.

Silver hair, pierced ears, short skirts, cigarettes, and parasites. To Kousaka, they were all symbols of impurity, and he would consider Hijiri Sanagi a manifestation of all of them put together. Meanwhile, Sanagi had no interest in Kousaka from the start, and didn't expect anything from him beyond providing her a room to kill time in. Even though they were close together, a tall, thick wall stood between them.


A week passed after he met Sanagi.

Usually, the intercom would sound, and Sanagi would open the door to come in immediately after, but today was different. Even once the intercom's echo faded, the door hadn't budged. Kousaka concluded that this visitor was not Sanagi.

He went to open the door, and found it was indeed Izumi. Once again, he wore a drab Chester coat over a worn suit. As usual, his hair was oily, and he had a beard resulting from neglecting shaving for two days or so.

Kousaka silently let Izumi inside and closed the door. Then he carefully passed by so as not to touch him, and turned away from the living room to face him.

"Seems you really hit it off with Hijiri Sanagi," Izumi commended with folded arms. "I didn't have any hope for you at all, but you've done pretty good, huh?"

"Thanks," Kousaka said bluntly. He figured it was wise to stay quiet about bribing her.

"I'd like to know for reference, just how did you approach her? I figure just making her feel comfortable must have been an ordeal."

"I just asked her to be my friend," Kousaka said, yawning. Due to days without sleep, his eyes were fogged over and his head was numb.

"The end."

He furrowed his brow. "Hey now, you're kidding, right? Just that got Hijiri Sanagi to keep coming to your house?"

"What reason would I have to lie?" Kousaka feigned ignorance, and Izumi snorted.

"I dunno what trick you pulled, but it's a big deal. You may be a jobless criminal good-for-nothing, but you've got a knack for kidnapping young girls." He clapped mockingly for Kousaka.

"Well then, let's move on to your next mission."

Kousaka stared blankly, at a loss for words. Next mission? Was becoming friends with Sanagi not the end? Don't tell me that after this was done, there'd be another mission, and once that was done... on and on like that?

Izumi informed him.

"Find out Hijiri Sanagi's worries. Of course, I don't want you to force it out of her, but naturally get her to tell you."

"Worries?", Kousaka repeated to confirm. "Does she have such a thing?"

"Sure she does. Nobody's without worry. All the more true for a girl around her age. Worrying's like your job then."

"That may be true in a general sense, but..."

"That said, I don't want you to find out if her skin's been bad lately, or her lunulae are a little bigger than normal people's, or the creases on her left and right eyes are in different places - any trivial worries like that, there's no point. What you need to find out is the reason for her lack of attendance."

Kousaka thought for a moment, then asked. "Is it not simply that she finds school annoying, for instance?"

Izumi grinned, but it was a somehow aggressive-feeling grin.

"As I thought. You're so sensitive to your own pain, but have such dull senses for the pain of others. That's the kind of guy you are," he said with a cynical look at Kousaka. "So I'm gonna emphasize for you here, Hijiri Sanagi's more of a normal girl than you think. And if a normal girl's dressing in a way that's not normal and doing things that aren't normal, that means something non-normal is happening to her."

Izumi took a step toward Kousaka and spoke overbearingly.

"And I'll give you one more warning. If you try to fool me, or you hurt Hijiri Sanagi, it won't end at telling people about the virus. You might be driven into a situation more stressful than you've ever dealt with before. Beat that into your head."

Kousaka nodded meekly.

But just a few hours later, he would unintentionally hurt Hijiri Sanagi.

Once Izumi left, Sanagi appeared as if taking his place. She didn't even glance at Kousaka, the room's owner, lay down on the bed which had become her personal seat, bundled up the pillow to put under her chin, and opened a book. I feel like a ghost bound to this place, Kousaka thought. Maybe I'm the spirit of a man who killed himself in this room, and hasn't realized he's dead yet. Ownership had already changed over to Hijiri Sanagi, but she was mistaking me as a visitor. That was a rather pleasing idea.

However, he couldn't indulge in considering himself a ghost forever. Now, Kousaka had a mission to find out the reason why Sanagi wasn't attending school. He would have to somehow initiate a dialogue with her, skillfully get to the subject of school, and have her naturally reveal the reason.

While he thought about how he could break the subject, his gaze was unconsciously focused on Sanagi. She took off her headphones, looked up, and belligerently said "What? Is there something you want to say?"

"Nothing like that." Kousaka hurriedly averted his eyes, and gave an on-the-spot excuse. "Um, I noticed you're wearing that earring again today."

"When I saw it before, I thought it was pretty. That's all, nothing else."

Sanagi blinked with suspicion. Then as if having forgotten about the earring's existence until just now, she gently touched her ear and felt it.

"Want to get a closer look?"

"...No, that's fine."

"I see." Sanagi put her headphones back on and returned to reading.

Her suggestion came as a surprise. Based on her usual attitude, the natural response would have been being ignored or disparaged.

Kousaka imagined. Maybe that blue flower-shaped earring has some special meaning to Sanagi. If someone complimented it, no matter who, it must have made her happy.

Truthfully, Kousaka didn't like earrings. Opening up holes in your body seemed unbelievable, and sticking something artificial in there seemed all too prone to bacteria. Did she take it out daily and disinfect it?

It wasn't only earrings; he had similar thoughts about wristwatches, smartphones, bags, glasses, and headphones. Even if you took daily showers, wouldn't it be pointless if the things you wore were dirty?

Kousaka turned his chair away from Sanagi, pulled himself together, and began to think how to ask about her worries. If he asked too directly, she might see through it and notice Izumi had put him up to it. How could I bring the conversation there naturally? I mean, I've never even had a regular chat with her.

Then Kousaka rethought it. There's no reason to do everything the way Izumi says. Moving from one lie to two was no big difference. I could be honest and tell Sanagi "Izumi gave me this instruction," discuss it with her, and pay to have her cooperation. Wasn't it that simple?

Kousaka stood up and said close to Sanagi's ear, "Sanagi, I wanted to talk about something."

"What is this this time?" She slid down her headphones and looked up at him.

"Izumi gave me a new instruction today. He told me to ask you the reason you aren't going to school in a natural way."

"Won't you help me out? You don't even have to tell me the truth. You can just fabricate a reason that'll convince Izumi."

Sanagi's response came after a significant delay. There was an irritating silence, like when trying to talk to a virtual assistant in a place with bad reception.

"He told you to ask in a natural way, right?" Sanagi turned her cheek away from Kousaka. "So why not ask me naturally?"

"I don't think I'll be able to do that, which is why I'm just asking. I'll give you suitable payment."

"I don't want to answer," Sanagi stated plainly.
"You can lie."
"I don't want to lie."

In other words, she didn't want to cooperate. Kousaka considered other things he could offer, but soon gave up and sat in his chair. There was no rush. Maybe she'd just gotten up on the wrong side of the bed today. Probing deeply now would just upset her. I'll ask another day, he thought.

It must have been the sleep deprivation; at some point, he fell asleep in his chair.

He felt something off about his shoulder. At first, he thought it was just an itch. But the feeling gradually became more solid. Something was poking Kousaka's shoulder. Soon, he realized it was someone's finger.

Someone's finger?

His hair stood up on end.

Kousaka acted reflexively. He batted away the hand poking his shoulder. When he did, he felt his overly-long index finger nail scratch the person's skin somewhere. He heard a small groan, which woke him up at once.

Sanagi's face was scrunched in pain, and she held a hand over her right cheek, scratched by Kousaka. When she removed her hand, he saw a wound about a centimeter long bleeding dark red blood. She slowly looked at the blood on her palm, then slowly looked toward Kousaka.

I did it again, Kousaka thought.

"...I was just going to say I was leaving," Sanagi said without inflection. "Did you hate me touching you that much?"

Kousaka hastily apologized, but Sanagi wouldn't hear it. With a scornful glare, she took her bag and left the room, slamming the door shut.

Kousaka just stood there for a while. The slamming sound of the door kept echoing deep within his ears. Then he remembered something, took off the bed sheets and pillow cover, went to the bathroom, and took off his clothes. He tossed them all in the washing machine, hit the switch, and took a shower.

She'll probably never come here again.

So he thought.

Kousaka couldn't speak about his obsessive cleanliness this late on. It had been a reaction he would demonstrate to anyone, not a special dislike of being touched by Sanagi. If he did honestly confess it to her, she might just take it as a poor excuse... but it would still be far better than not explaining anything. It was even possible that she would later see how it shed light on Kousaka's actions and behavior, and in time understand.

However, he had already let that chance slip by. It's all over now, Kousaka thought deeply. Izumi won't forgive me for hurting Sanagi both physically and emotionally.

After showering and returning to the living room, Kousaka came to a stop. He was too distraught to notice earlier, but there were a few bloodstains on the floor. They must have dripped off the wound on Sanagi's face. He squatted down and looked closely.

Since he considered other people a symbol of impurity, blood was a very detestable thing. Normally, he would have wiped it up without a second thought. However, for some reason, he felt as if these bloodstains should be left there. It wasn't quite as "punishment." He didn't quite understand it himself, but maybe the more appropriate term would be "commemoration," he thought.

He sat in his chair, staring endlessly at the stains. Then he thought, I shouldn't be doing this; I'll think about something more fun.

...Yes, like SilentNight, for instance. That worm has already scattered to all corners of the mobile network. Whatever happens to me now, likely no one will be able to stop the force of SilentNight. Even if Izumi goes running to a security firm right now, it's probably too late. On December 24th, the worm should definitely activate and render a large number of smartphones useless. The streets should be filled with people who can't meet up with their friends. He felt so comfortable picturing it.

Of course, it wouldn't just be a simple prank. While SilentNight was designed to make an exception that restored communications when an emergency number was called, there could be people whose lives were ruined by the effects of this worm. Even fatalities wouldn't be surprising. If his criminal acts were discovered, he would bear a heavy sin.

But do I care?, Kousaka harshly thought. There's hardly anything left for me to lose. He couldn't even find meager memories to cling onto.

For a few days afterward, Kousaka led an even more decadent life than before. He didn't even touch his computer anymore, sleeping in the corner of his bed and quietly waiting for judgement to be passed down on him. The only things he did were clean and do a series of washing rituals. He found eating a chore, not putting anything in his mouth but water and functional nutritional food. After four days, he ran out of food, so he only lived on water. And he left the blood that fell from Sanagi's cheek in its conspicuous location.

It wasn't the first time his disorder had caused injury to someone. He had made mistakes similar to this one many a time. There were too many minor incidents to count. He naturally came to be disliked by most people, but what was more painful was when he did things of the utmost rudeness to the occasional person who extended their hand cordially.

Their expressions when he wounded them had all burned themselves into Kousaka's mind, without exception. If it had just been a misunderstanding that angered them or made them hate him, he could cover his ears and hang his head. But the guilt of denying a simple gesture of kindness couldn't be rid of, not even by that superb doctor known as time.

Usually, Sanagi had left the room without a word when going home, so her trying to wake Kousaka up to say goodbye might have been a sign that she'd opened her heart to him after he complimented her earring. If that was the case, then he really had stomped all over her good will.

Just how long will I keep repeating this?, Kousaka wondered. "Someone might as well kill me off while I sleep," he tried saying aloud. That idea he voiced on a whim resounded in his mind, feeling perfectly right. No doubt this is what I really want, he felt.

In that case, what have I been living these 27 years for?

Maybe they were 27 years of looking for a way to die. I can't find a way to live, so I at least want to settle on how I'll die. If that theory is correct, then as long as I find a suitable way, I can move to carrying it out at any moment.

Kousaka had a crystal-clear image. He wakes up in a bed at a school infirmary. The room is dark, and totally silent. There are cloudy skies outside, and looking closely, he can see it's snowing. It doesn't look as if there's anyone but him here, but he can feel a sort of disturbance in the air from someone leaving a moment ago. Listening close, he hears doors opening and closing, and footsteps. All of them sound so far away. ...Was I sleeping for a while? He gets uneasy, and looks up at the clock. Perhaps the whole day went by while I slept? But he's worrying over nothing, as it's only 4 PM. It's still fine to sleep. Relieved, he lies back down, wraps himself in the blanket, and softly closes his eyes. And he never wakes up again.

It'd be nice to die like that, he thought.


The call came the afternoon of December 10th, four days after Sanagi stopped coming to the room. When Kousaka heard the sound, he almost unconsciously grabbed the smartphone, and seeing the words "Hijiri Sanagi" on screen, immediately pressed the call button.

"Hello," he said into the phone.

There was a long blank. As he was starting to question if Sanagi's phone was malfunctioning, she finally spoke.

"I'm under Sagae Bridge."

Kousaka searched his memories. He felt like one of the bridges over the river which separated the residential area his apartment was in and the central part of town was named that.

"And?", he asked.
"Come meet me."

Maybe it was just because it was over the phone, but her voice seemed weak, without the usual thorniness.

"...Sorry, but I can't deal with the outside."
"I know. But I want you to come."

"Please," Sanagi appended. Kousaka wondered if this was actually Hijiri Sanagi he was talking with. He couldn't believe that girl would be this modest.

"Got it," he casually affirmed. He didn't get the situation, but he could tell it was pressing. "I'll head right there. I think I'll be there in thirty minutes."

"...Thank you," Sanagi said in a wispy voice.

After hanging up, Kousaka donned a face mask and latex gloves, checked that he had his anti-bacterial goods in his bag, and left the apartment fully prepared.

Likely as a result of having the curtains closed all the time he'd been indoors, his eyes just couldn't adjust to the brightness, despite the sunlight not being particularly strong. The sun reflected off the snow piled on the ground, continually pricking him in the eyes. He should have only lost weight in these past few days of unhealthy living, but his body felt heavy. His muscles must have weakened.

Though the trip would have been ten minutes by bus, he spent many times longer walking that distance. Finally, Sagae Bridge came into sight. He went down the embankment stairs and along the sidewalk. By the pier of the bridge, he saw someone crouching and hiding their face.


Kousaka spoke from beside her, and Sanagi slowly looked up. It was dark from the shadow of the bridge, but he could plainly see how unhealthy her face looked. Though it was the middle of winter, her neck was wet with sweat.

"Are you feeling sick?"

Sanagi shook her head. It seemed to indicate "no, but it's hard to explain."

"Can you stand?"

She stayed silent. Rather than not wanting to answer, it seemed she wasn't sure of the answer herself.

"There's no rush," Kousaka said with concern for her. "I'll wait until you're better."

Kousaka nervously sat down about 50 centimeters away from Sanagi. Truthfully, he wanted to leave this damp and stagnant place as soon as possible, but he thought it would be too cruel to rush her right now.

A good hour passed, and Sanagi finally got up. Kousaka stood up after her, and she modestly grabbed the sleeve of his coat. He was able to bear that level of indirect contact.

The two began to walk. Suddenly, Kousaka realized the headphones Sanagi always wore were nowhere to be found. Maybe that was what made her look so defenseless today.

For a while after arriving at the apartment, Sanagi held her knees on the bed. Kousaka tried asking if she wanted something warm to drink, but she didn't respond. Soon the sun started to set, so he went to turn on the lights, but Sanagi said "Don't turn on the lights." He withdrew his arm.

Nearly an hour passed after that. The sun fully set, so the room was pitch black except for the unpleasantly bright computer and router lights.

Sanagi stood up with no previous notice and flipped the lightswitch. The pale artificial light lit every corner of the room, and everything's shape became clear. Then she went back to bed and lay down with the pillow under her chin as usual. But she didn't open a book.

"What happened?", Kousaka asked.

Sanagi started to turn, then gave up part-way and sunk her chin back into the pillow.

"There's some reason you can't go back home alone, right?"

After a long pause, Sanagi acknowledged it. "Yeah."

"...Um," she spoke. "I'm scared of making eye contact with people."

"What do you mean?"

Then Sanagi explained, in a halting manner.

"I'm totally aware it's overly self-conscious. But it's just no good. Every person I meet, it feels like they're staring right at me. But I mean, it's not their gaze itself that's the problem... See, when you think "I'm being looked at," you look their way too, right? And when you do, even if they were actually looking someplace else, they feel your eyes on them and look at you. When I make eye contact like that... it feels so bad, I can't describe it in words. Like someone stomping around your house in dirty shoes, rummaging through your closets and drawers - that kind of unpleasant feeling hits me."

Kousaka was taken aback. Now that she mentioned it, from the time they met until now, he'd hardly made eye contact with Sanagi. Their eyes had crossed paths for an instant numerous times, but maybe there was no moment that could really be called "eye contact."

Sanagi went on. "But that doesn't mean I can just never go outside, or walk around with my eyes closed, right? I tried to see if there was anything I could do, and found out that relying on certain objects can lessen your symptoms. I tried a bunch of things, but... for some reason, the most effective thing wasn't glasses or a face mask or a hat, but headphones."

"Ah..." Kousaka nodded with understanding. "So that's why you always wore such big headphones?"

"Yeah. Doesn't make much sense to cover my ears because I'm scared of eye contact, huh." Sanagi laughed self-derisively.

"Nah." Kousaka shook his head. "I think I get it."

He wasn't lying. He knew all too well from his own experience just how illogical compulsions could be, and it wasn't Kousaka's first time hearing about scopophobia. In the process of reading through books about mysophobia, he acquired knowledge of other compulsive disorders whether he wanted to or not. He had read somewhere about people who couldn't walk through crowds without headphones. And about people who were scared of people looking at them, yet purposefully dressed strangely and dyed their hair conspicuous colors.

Kousaka could understand their feelings to an extent. The reason headphones proved more effective at surpressing Sanagi's scopophobia than sunglasses or face masks was probably that occupying her sense of hearing diluted the feeling of "being there." And she might have purposefully dyed her hair a flashy color and dressed in an attention-grabbing way to protect her fragile heart, or perhaps as a feint of sorts for those around her. Like an insect that mimics the dangerous coloration of a wasp to avoid predators, if she acted like a delinquent at least in appearance - while it might get more eyes on her - it would reduce the instances of actual eye contact.

"I see... Scopophobia...", Kousaka affirmed once more. "I didn't notice at all until you told me. You hid it well."

"...Maybe in front of you. But it doesn't go like that with others." Sanagi snuck a look at Kousaka, then turned back. "You don't try to look people in the eye when you talk, do you?"

She was exactly right. While it didn't go as far as scopophobia, Kousaka was also poor at looking people in the eye (though naturally, the reason wasn't finding other people's gaze scary, but not wanting to look directly at their dirtiness).

At this point, he finally realized what Izumi meant by "suitability." In short, this girl would only get along with cowards who couldn't look her in the eye.

Sanagi slowly began to tell the circumstances leading up to her calling Kousaka.

This afternoon, she headed for the library like usual. While returning a book she'd checked out and looking for a new one to borrow, all of a sudden, she noticed her scopophobia symptoms were less severe than usual. Maybe going to visit Kousaka daily was now starting to show its effect.

She stopped and thought. While I'm rehabilitating, how about I read here in the library? It being a day off, the library was rather crowded, but maybe it would be more effective training to have this stimuli.

Sanagi sat in an empty seat and opened her book. At first, she wasn't able to focus due to glances she was only imagining, but she gradually narrowed her vision and could focus only on the words.

After reading about halfway, she decided to take a break. She stood up to loosen her stiff body, and wandered around between the bookcases. She liked walking around the library like this for no particular reason. She enjoyed taking books she had no interest in the contents of and just checking their binding, shape, weight, smell, and feel.

It couldn't have been three minutes since she left her seat. But when she came back, something important was missing. The headphones she'd hung on the chair were nowhere to be found.

Sanagi immediately looked around. The book she was reading was there on the seat, and her other belongings were still there, so it seemed unlikely that the headphones were considered a lost item and taken away. They'd been stolen.

She cursed her carelessness for getting out of her seat and leaving her headphones behind. Without those, she couldn't walk through crowds or ride the train - how could she have neglected them?

She put the book in her bag and left the library with an uncertain gait. Should I take an hour walking home, or endure and take the train? Both felt equally difficult. I'll take this optimistically, she told herself. You could think of this like my chance. Once I overcome this trial, I'll know for sure my disorder has gotten much better than before.

But not five minutes after leaving the library, her heart was torn to shreds. She couldn't remember how she'd walked around outside before. What expression she had, where she placed her gaze, how fast she walked, how she swung her hands. The more she thought about it, the more awkward it felt, and her scopophobia intensified. To get away, she went off the road and down stairs, hid under Sagae Bridge, and grasping at straws, called Kousaka.

That was the end of the story.

"...I thought I was getting better," Sanagi mumbled at the end.

For a while, Kousaka listened to her sob.

He knew painfully well how it felt to lose confidence and become timid after a fit like this. And he knew that consolation with words had almost no effect at these times. So Kousaka was silent. He'd let her keep crying.

But contrary to his expectations, Sanagi quickly stopped crying. She wiped her tears, took a deep breath, sat up and turned over, and sat on the edge of the bed. And for a moment, she gave Kousaka a meaningful glance.

Maybe Sanagi's expecting something from me. Or maybe I want to do something for her, so I'm projecting it onto her glance. Either way, the conclusion was the same. I should do something for Sanagi, Kousaka thought firmly. Unlike me, she's at an age where she still has a lot to sort out, where you're fragile and easily-hurt. Now is the time she needs support the most.

Kousaka sat down next to Sanagi. And he timidly offered his hand. His bare hand, since he'd taken off his gloves on returning to the room. And he touched Sanagi's head.

Instantly, numerous disgusting words like "pores," "oily skin," "keratin," "staphylococcus epidermidis," and "Demodex folliculorum" ran through his head. But Kousaka temporarily put them off with a shudder. If he was going to scream, he would do so as much as he liked after she left. But now wasn't the time.

Sanagi lifted her face in surprise. But she didn't show any dislike.

Kousaka awkwardly moved the hand placed on her head.

He was intending to stroke it.

"...You don't have to push yourself," Sanagi said with a sigh.

"I'm not pushing myself," Kousaka said with a smile. But she could feel his body trembling through where his hand was touching.

He obstinately stroked Sanagi's head. Maybe he figured that he'd probably never do this again once it was over, so it was better to get plenty of it in now.

"That's enough," Sanagi refused, but Kousaka wouldn't listen, saying "No it isn't."

"All right, all right. I'm feeling better. You can stop consoling me."

Hearing that, Kousaka finally removed his hand from her head.

"Did that distract you?"

"Are you stupid?", Sanagi said with a look of shock, but seemingly wouldn't deny it did. Her voice had regained some of its cheerfulness.

"I'm really sorry about injuring your cheek," Kousaka apologized. "Does it still hurt?"

"Nah. This is nothing." Sanagi ran a finger over the scabbed wound. "...Going to wash your hands?"

"No, this is fine."

Kousaka stared at his right hand, used to touch Sanagi. It was still trembling slightly, but he managed to resist the urge to go take a shower right away.

"I'll tell you something funny," Kousaka said.
"Something funny?"

"To tell the truth, I'm a clean freak."
"...Yeah. I know."

"Of course." Kousaka smiled wryly. "I feel like people other than myself are horribly dirty. Just being touched by them, just touching something they touched, just breathing the same air, makes me feel like I'll be sick. I know better than anyone it's just an issue of feelings and nothing more. But there's nothing I can do. I tried various treatments, but they just made it worse."

Kousaka glanced to check Sanagi's expression.

"Go on," she said.

"Even when I first got a girlfriend, I couldn't kiss her, or even hold hands for that matter. One day, she treated me to her own cooking. She was good at that kind of familial stuff. And her cooking was well-done. But even though she'd put in all that effort to make it for me - or maybe that was exactly why - I was incredibly hesitant to eat it. As much as I tried to consider it as food, I couldn't bear it just thinking that she'd touched the ingredients. Honestly, I didn't want to take a single bite. And yet, I knew it would be rude to just refuse the meal she'd made, so I emptied my head and just forced it down. What do you think happened?"

Sanagi silently shook her head. Like saying she didn't even want to think about it.

"After eating about half, I threw it all up right in front of her. I can't forget the look on her face. We broke up not ten days after that. I still have dreams about it sometimes. The meals get more elaborate every time. And since breaking up with her, I've never had anything like a girlfriend again."

Sanagi slowly shook her head. "...That wasn't very funny."

"Really? Isn't it at least a little funny that I haven't ever kissed anyone at age 27?"

After Kousaka's funny story bombed, Sanagi got off the bed and did a big stretch. Then, thinking of something, she reached for a dispenser on a shelf and covered her hands in disinfectant. Then she carefully put disposable latex gloves on them and even put on a face mask, and turned toward Kousaka once she was ready.

She gave him no time to ask what she was doing.

Sanagi grabbed Kousaka's shoulders with both hands and, through a face mask, put her lips on his.

Though a thin cloth separated them, he did faintly feel her soft lips.

By the time Kousaka understood the intent of her actions, she had pulled away.

"You'll have to endure with that," Sanagi said, taking off the mask.

Kousaka had no words, halted like a toy out of batteries. He might have even forgotten to breathe.

"What are you trying to do?", he asked at length.
"I felt sorry for you, so I gave you a kiss. Thank me."
"...That's very polite of you."

Following Kousaka's confused thank-you, Sanagi made an addition.

"Besides, I've never had one myself, so I guess it was just right."

He didn't know what exactly she meant by "just right," but from her expression, it didn't seem to be a bad thing.

"...Well then. It's time I say farewell."

Sanagi stood up and grabbed her bag.

"Can you get home alone?", Kousaka asked with concern.

"Yeah. It's not too far, and it's less crowded by now."
"I see..."

Kousaka judged from her tone that she would probably be fine.

Then he had a sudden thought, opened the bottom drawer of his desk, took out headphones, and put them around Sanagi's neck.

"You're sure? You realize I'll get them dirty?", Sanagi asked with a slightly nervous look.

"I won't use them again, so you can take them."

Sanagi put her hands on the headphones and spoke happily. "...I see. You're a lifesaver. Thanks."

"Right. Good night, Sanagi."
"Good night, Mr. Kousaka."

She smiled, looking right into Kousaka's eyes.

After Sanagi left, Kousaka sat in his chair and closed his eyes, just thinking aimlessly about the events that had just transpired. He repeatedly thought pointless things like "come to think of it, that was probably the first time she called me Mr. Kousaka."

After about thirty minutes, he was suddenly struck by the fact that he still hadn't started cleaning or taken a shower. It had been a long time since he'd gotten away from his cleaning tendencies for that long.

Something inside me is starting to change. So he felt.


Chapter 4: This Wormy World

Kousaka put on gloves, leaned back deep in his work chair, and opened a magazine. As one might expect, it was a science magazine concerning parasites. The cover read "The Journal of Parasitology," and the contents were all written in English. Kousaka was impressed. So she could read English as complex as this at her age.

Flipping through, he found a page with a tag on it. A paper by Norman R. Stoll, titled This Wormy World. Kousaka wasn't sure how to translate it. Did it mean a worm-eaten world? Or a world that was like a worm? No, he couldn't forget that this was a paper on parasitology. So then, perhaps "this world brimming with parasites" might be most correct.

The sound of showering from the bathroom ceased. About five minutes later, Sanagi appeared, changed into pajamas. Seeing her with a black towel on her head, Kousaka muttered a "huh" of some surprise.

"What is it?", Sanagi asked.

"Oh, it's nothing big... I just thought that with your silver hair covered like that, you looked like a normal girl."

Sanagi's eyes flickered, and she pointed to her head. "Oh, this? Sorry for being a non-normal girl."

"I'm not saying your hair is bad or anything. It just felt fresh seeing how it would look black."

"I figure you like girls with black hair, fair skin, polite and without any piercings anyway, Mr. Kousaka," Sanagi said maliciously, sitting cross-legged on the bed.

"I didn't say anything like that."
"Then how do you explain all that stuff on your computer?"

"...What do you mean?"
"Kidding. Just wanted to tease you."

"You can't make jokes that ominous." Kousaka sighed, leaning back.

Sanagi suddenly noticed what was in his hand, and her eyes widened. "Hey, that magazine's..."

"Yeah." He'd completely forgotten about the magazine until she pointed it out. "Sorry, I'm always just curious what you're reading. Should I not have gone and touched it?"

"Not really, but... What did you think of it?"
"It was a little tough for me. Are you good at English, Sanagi?"
"Nah. I don't get very good test scores."

"But you can read academic papers?"
"Only in this one field. They all have similar composition, so I've gotten familiar with it."

"That's a big deal. I'd like to tell that to a slacker college student." Then Kousaka aired the question he'd had earlier. "By the way, how do you translate this part?"

Sanagi stood up and came behind Kousaka, looking at the part he was pointing at over his shoulder. The sweet smell of shampoo tickled his nose. She was at a distance he'd normally back away from, but since she'd just showered, it was fine.

"You're an adult and you don't know something that simple?", Sanagi said teasingly.

"Adults aren't quite the fantastic creatures you think they are," Kousaka retorted. "So what does it mean?"

"I think it was translated "this world full of insects" in a book I read once," Sanagi mused, as if searching her memory. "It was famously used in 1947 by Norman Stoll to describe the world as one where parasitic diseases run rampant."

"That's one horrifying phrase." Kousaka furrowed his brow.

"Incidentally, even over half a decade later, the situation is almost unchanged. People all around the world unconsciously have many types of parasites in their bodies. And Japan's no exception. Certainly well-known parasitic diseases like ascariasis, schistosomiasis, and malaria have gone away, but parasites naturally lurk in many places in our bodies, waiting for a chance to infect. Or maybe they've already infected, but the person never even realizes it."

Kousaka sighed. "Sounds like the mind of a clean freak will never know rest."

Sanagi said she'd go dry her hair and left the living room.

Since that day they told each other about their disorders, Sanagi had begun taking showers before she entered the living room. Kousaka said she didn't have to show that much forethought, but Sanagi said "It's my prerogative, right?" Once she'd washed, she'd put on a fresh change of clothes she brought, enter the living room, lie on the bed, and read, and talk to Kousaka if she felt like it.

After returning from the bathroom, it seemed Sanagi still wanted to talk, so rather than lie on the bed, she sat across from Kousaka.

Then Kousaka asked her. "It looks like you're always reading books about parasites. What is it about parasites that captivates you so much?"

"...I could tell you, but you might feel sick and faint, okay, Mr. Kousaka?"
"If I hear it in this room, I think I'll be okay."

"Let's see..." Sanagi put her hand to her chin and pondered. "Mr. Kousaka, have you heard of Diplozoon nipponicum?"

When Kousaka shook his head no, Sanagi began explaining the ecology of that parasite. Their lifelong copulation, their appearance coming to resemble a butterfly, their fated love at first sight, the blindness of love, worms that were two peas in a pod. After talking for a while, Sanagi suddenly became aware of how talkative she was being and her face reddened, but Kousaka said "Keep talking," so she talked a little more.

"This earring." Sanagi parted her hair to show Kousaka. "This is modeled after a parasite too."

"It just looked like a blue flower to me. So there's a parasite shaped like that?"

"Right. It's called Kudoa septempunctata, and it belongs to the Myxozoa. These parasites use both fish and annelids as alternating hosts, and each of their spores has six to seven flower-petal-shaped structures called polar capsules, so it looks like a full flower from above. The D. nipponicum keychain is a little exaggerated, but if you dye K. septempunctata blue, it really does look exactly like this earring. Look it up."

As instructed, Kousaka did an image search for "Kudoa septempunctata" with his smartphone. And indeed, many images came up of tiny organisms under a microscope that looked just like Sanagi's earring.

"The spitting image, right?"
"I'm surprised there's a parasite this pretty."
"Well, it causes food poisoning, so it's a harmful one to humans."

Kousaka put down his phone. "Are there any more interesting parasites like this?"

"Hmm, well, let's change course a little for the next one." Sanagi folded her arms and thought for a while. "Since you're such a clean freak, even without studying parasites, I'm sure you know Toxoplasma gondii?"

"Yeah, naturally." Finally, a name he recognized. "They're parasites that transmit from cats to humans, right?"

Sanagi nodded. "Yeah. They're famous as the cause of toxoplasmosis. Their final hosts are cats, but they can infect most warm-blooded animals, which of course includes people."

"Final host?", Kousaka asked, an unfamiliar term coming up quickly.

"The host that's the parasite's final destination," Sanagi explained in layman's terms.

Some kinds of parasite will infect different hosts in various stages of growth. For instance, Anisakis, nematodes that are the cause of anisakiasis, first incubate in water, then are preyed upon by crustaceans such as krill. They avoid digestion and survive in their bodies until becoming a stage three larva. Next, the crustacean is eaten by a fish higher up on the food chain, and the Anisakis continues to mature inside the fish's body. Then the fish is eaten by a whale, and the Anisakis can pass stage four as a larva and become an adult within the whale's intestine. The eggs laid by the adult mix in with the whale's excretions and discharge into the water.

This is the life cycle of Anisakis. In its case, the crustacean would be the "first intermediate host," the fish the "second intermediate host," and the whale the "final host." A final host is a parasite's final destination. If it can't infect its final host, the parasite can't reproduce.

"...So, back on topic. How many infected by Toxoplasma do you suppose there are worldwide?", Sanagi questioned.

"You say they can infect most warm-blooded animals, so I'm sure it's a pretty big number. A few hundred million people?"

"Over one-third of the population," Sanagi said readily. "A few billion people."

Kousaka's eyes went wide. "That many?"

"If we restrict it just to Japan today, I guess the ratio might be a little lower. Maybe ten or twenty percent at best."

"Either way, that's still a lot. ...But on the other hand, that's proof that Toxoplasma is harmless to humans, right? If that weren't the case, I'd think there would be a big panic by now."

"Yeah. It's no problem if it infects healthy people. And so far, it's been deemed harmless to anyone but those with immunodeficiency and pregnant women. But lately, there's been talk about the possibility of them altering people's actions and personalities."

Sanagi poked at her forehead.

"There's been interesting research about the effects of giving Toxoplasma gondii to a host. Male rats who are infected with these protozoa stop fearing cats, who should be their predators. Apparently the Toxoplasma controls the rat, using it as an intermediate host, to make it easier to be eaten by its final host, the cat."

"It controls the host?" Kousaka's voice cracked in horror. Wasn't that just like Heinlein's book The Puppet Masters?

"When they dissected the infected rat, the area around the cerebral limbic system had a huge number of cysts. And when they analyzed the DNA of Toxoplasma gondii, they found the presence of genes relating to the creation of dopamine. I don't know the exact mechanisms, but it seems like Toxoplasma can control a host for the convenience of its own reproduction. In fact, parasites controlling their hosts is a common thing. Dicrocoelium and Leucochloridium are famous examples. Both are known to cause suicide or starvation in intermediate hosts."

Kousaka thought a little, then spoke. "So you mean something similar could happen in human brains infected by Toxoplasma?"

"That's right. Recent research shows that a man infected with Toxoplasma gondii shows a more favorite reaction to the smell of cats than a man who isn't infected. However, it seems the opposite was shown in women."

"That's strange. There's a gender difference in the effects of parasites?"

"I haven't heard much about it with other parasites, but it's a trend I see with Toxoplasma research. There are results showing that infection by Toxoplasma gondii causes men to become antisocial and be disliked by women, while women become social and are liked by men. There was also a report that for women, there were 1.5% more who attempted suicide among the infected than the uninfected."

"So Toxoplasma might induce suicide in women?" Kousaka shuddered. "And over a third of the world's population is infected with a parasite like that?"

"It's just a possibility. It's not proven."

"...Even so, it makes me shiver," Kousaka said with a sour look. "They say Pasteur became a germaphobe because of his studies in microbiology, so I feel like the more I learn about things I can't see with the naked eye, the harder it'll be to live in this world."

"I've got plenty more spine-chilling stories where that came from. Want to hear?"

Kousaka shook his head. "No, let's change the subject. Sanagi, do you have any interests besides parasitology?"

"Hmm... It's a secret." Sanagi put her finger to her lips mischievously.

"Is it a hobby you can't tell people about?"
"It's a girly hobby."
"Normally you would be public about the girly hobby and hide the parasite-loving."

"Standards for embarrassment will vary," Sanagi retorted with displeasure. "You tell me, Mr. Kousaka. What captivated you about making viruses?"

Kousaka told the story of acquiring an interest in malware. How a text message about the end of the world saved him somewhat. How he wondered if he could make something similar himself. How he found once he started that he was unexpectedly suited for it, and it even ended up being what he lived for.

"I think I kind of understand feeling saved by a message about the end of the world," Sanagi agreed. "By the way, what kind of virus were you making?"

"Do you know about the first computer virus recognized in Japan, Sanagi?"


"Japan's first domestic virus was developed in 1989. It was a sort of playful virus called Japanese Christmas that just displayed a festive message on computers on December 25th. Similarly, the malware I made will activate on Christmas Eve. Though I think the damage it'll bring about will be a little more serious."

Sanagi moved her chin just a few millimeters, urging him to continue.

"Strictly speaking, what I made is a worm that isolates people," Kousaka explained, trying to break it down. "Infected smartphones can't do any communication from the evening of Christmas Eve to Christmas night. I figured it would mess up couples trying to meet up all over Japan. ...Funny, isn't it?"

But Sanagi didn't laugh.

The moment she heard Kousaka's words, her eyes widened and she became still, as if struck by a bolt of lightning.

"What's wrong?", Kousaka asked. Sanagi's eyes remained fixed on his throat, and she didn't reply. And perhaps her eyes didn't see anything.

Sanagi didn't move for a while, silently pondering. As if she'd found a crack in the world, she kept staring at the same point in space. If you listened closely, maybe you could hear the gears rapidly spinning in her head.

Maybe something in my words disturbed Sanagi, Kousaka realized. But he couldn't identify anything that had such power in what he'd said.

In the end, Sanagi never explained why she suddenly went silent, and awkwardly changed the subject. But even while chatting about different subjects, it seemed her attention was still focused on "something" from earlier.

It only figured that she would be disturbed. Because the malware Kousaka created, as it happened, was just so similar to something else she knew of.


It was his weekly shopping day. Holding shopping bags in both hands, Kousaka walked down the road lit by streetlights. Water that had faintly pooled in places on the road shone darkly. The air was clear, and you could see even small stars with the naked eye.

He saw a middle-aged man sitting on a roadside bench encircled by trees. When the man saw Kousaka, he put his can of coffee on the bench and stood up.

"Hey," Izumi said, raising a hand. "Looks heavy. Need a hand?"

"I'm fine." Kousaka turned him down. "...Checking on my progress?"

"Well, more or less."

Izumi was in his usual get-up, a drab Chester coat over a suit. Did he not have any other coats? Or maybe he decided to always wear this when he met Kousaka? Or maybe it was simply that he didn't care at all about clothes.

Izumi sat back on the bench and glanced at Kousaka's shopping bags. "I've been wondering, what does a clean freak eat?"

"Cereal, nutritional foodstuff, tofu, canned goods, frozen vegetables..." Kousaka listed off the contents of his bags. "There's a lot I won't eat, sure, but I'm not particularly limited. And I don't generally eat a lot."

"Meat? Sashimi? Raw vegetables?"
"I hate oily things, so I can't eat meat. Sashimi is a definite no. I can eat raw vegetables if I clean them well and cook them myself. Though I don't think about wanting to eat them because I like to."

"I'll drink only whiskey, if I'm told to."

But that only applies to medicine-esque whiskey like Laphroaig and Bowmore, Kousaka thought to himself.

"Well, that's good," Izumi nodded, finding it plausible. "There's lots of people who can't drink whiskey and aren't clean freaks. In that sense, you're pretty lucky."

Kousaka sat down beside Izumi and put his bags on the ground. The cans in the bag clinked up against each other. After pulling the face mask dampened by his breathing down to his chin, he spoke.

"The reason Hijiri Sanagi hasn't been attending school is scopophobia."

After a few seconds, Izumi asked, "Did you hear that from her mouth?"

"Yeah. Her headphones seem to be for easing her symptoms."

"...Hard to believe," Izumi said doubtfully. "Did Hijiri Sanagi really say that? This isn't just some guess of yours, is it?"

"Have you not heard anything from her?", Kousaka inquired.

"She won't tell me anything about herself. It's a total mystery."

I see, Kousaka thought to himself. From Izumi's face just now, he could surely conclude that there was some level of communication between Izumi and Sanagi.

"She happened to have an episode of scopophobia and called me for help. If it hadn't been for that, I probably wouldn't have been able to find out for quite some time."

"She called for help?", Izumi repeated, as if struck off-guard. "This is shaping up to be a hell of a surprise. Can't tell what'll happen with you. And I figured you had the least promise of anybody I'd hired to date..."

"She probably had no one else to depend on then but me. I was just lucky."

"No, I don't think that's it. You're the first person to find out why Hijiri Sanagi hasn't been going to school. Until now, no matter how weak-hearted she's been, she's never revealed her scopophobia to anyone except relatives. In other words, she trusts you as much as a relative."

I'm as happy as can be if that's true, Kousaka thought. But he couldn't take Izumi at face value. Maybe he was fabricating this as a way of flattering Kousaka. It wasn't too strange to think that all the people hired before him had been taken by this tactic.

Izumi took an envelope out of his coat's inside pocket and handed it to Kousaka.

"Your payment. But it's only half. Whether I'll pay you the other half depends on your actions after this."

Since it was half, that meant it would match what he'd paid Sanagi. Relieved his investment came back to him, Kousaka put the envelope in his pocket.

"...So, what should I be doing next?"

Izumi didn't have an immediate answer, leaning back in the bench and looking at the sky. Kousaka also leaned back and looked upward. He thought maybe it had started to snow, but that didn't seem to be the case. Izumi was pondering something. It almost looked like he was searching the countless stars to find an answer.

Izumi took a drink from the can of coffee beside him, breathed, and answered the question.

"You don't have to do anything."

Kousaka turned to Izumi with wide eyes. "So does that mean my job is -"

"Hey, I didn't say that. Your job isn't over just yet. By "you don't have to do anything," I mean "keep things as they are." Keep being a reliable friend to her like you have. If you do that... maybe something interesting'll happen."


Izumi ignored his question.

"That's all from me. I'll contact you again later."

With that blunt remark, Izumi got up from the bench. It looked like he was going to just leave, but he suddenly stopped and turned.

"Forgot to say something important. A thing I should warn you about."

"What is it?"

"Whatever happens next, don't cross the line with Hijiri Sanagi. Even if that's what she wants from you. I doubt I need to worry about a clean freak like you, but I'll put it out there as a "just in case," against all odds. Keep it platonic, like Signal and Signaless."

Kousaka looked at Izumi dumbfounded. Then after a delay, he furrowed his brow.

"What are you talking about? You do know how much of an age difference there is between us?"

"Just tell me "yes." I'm not saying this out of concern for Hijiri Sanagi, I'm saying it for you. If you ignore that warning, you'll be the one in the most trouble. Up to you if you'll believe that or not."

Kousaka sighed. "You have no reason to worry. I won't even be able to hold her hand."

"Right. I'll be praying it stays that way."

With that, Izumi vanished into the cold darkness.


Kousaka was summoned by Sanagi via a phone call. It wasn't a desperate call like last time, but there was a sense of her having some business for him.

"There's something I want to try. Come to the library right away."

With only those words, Sanagi hung up. Kousaka hesitated for a while, but soon gave up, changed clothes, donned his gloves and face mask, and prepared to go out. But just before he left the room, he resolutely took off the mask and threw it in the trash can. He didn't know why himself, but he thought it would be better that way.

Sanagi was waiting for him on the stairs by the front door of the library. As usual, she was dressed in a way that seemed to leave her legs cold, and she was in fact shivering slightly, but she seemed to consider this shaking natural. When she saw Kousaka, Sanagi took off her headphones and raised her hand a little.

"What did you want to try?", Kousaka asked.

"I can't answer that right now. I'll tell you in a little bit."

Sanagi stood up. They walked together.

On the walk to the apartment, Kousaka kept stealing glances at Sanagi's face. He hadn't thought anything of it before, but after Izumi's unfair suspicions, he was acutely aware of Sanagi today.

Kousaka tried asking himself: Could I see this parasite-loving, scopophobic girl in a romantic way? Soon, an answer came back. "Not a chance." Indeed, it was the undeniable truth that I felt no special feelings toward Hijiri Sanagi. But I did have a perfectly natural fondness for her simply as someone dealing with similar worries, which was out somewhere very far from romance.

Kousaka laughed off his unease - idiotic. She was still a kid in her teens. Izumi couldn't have been speaking seriously, either. Just making extra, extra sure, no doubt.

Suddenly, he noticed Sanagi was looking right at him. He was worried that the things on his mind were showing on his face, but it didn't seem that was it.

"Hey, Mr. Kousaka. If I asked you to stroke my head again right now, what would you do?"

For a moment, Kousaka couldn't respond to the unexpected question.

"You want me to do that?"
"Just hypothetically. Could you? Couldn't you?"

Kousaka mentally evaluated the hypothesis.

"If I tried, I don't think it would be impossible."
"Yeah, right?"

"When I'm walking with you like this, I'm fine without headphones."

Now that she mentioned it, she'd taken her headphones off at some point and put them in her bag.

"It looks like when you're here, my scopophobia gets a little better. Maybe it could be relief from having someone who properly understands my symptoms around. What about you, Mr. Kousaka?"

Kousaka suddenly put his hand to his mouth. And it hit him. That was more or less why he'd removed his face mask before leaving the room. There must have been a sense of relief knowing he was meeting up with Sanagi, so he felt more at ease than usual.

"Yeah, I guess when I'm with you, my phobia is a little less intense, too."

"I knew it," Sanagi said proudly. "I don't really get how, but we can't not make use of this."

"Make use of it for what?"

"Isn't that obvious? Training ourselves to get used to the outside world. A three-legged race of rehabilitation, so we can walk around outside without gloves or headphones."

"...I see. That's not a bad idea," Kousaka affirmed.

"And so I did some thinking..."

Sanagi quickly began to outline her plan.

December 17th, Saturday.

Thinking about it, it was the first time Sanagi came to the room before noon.

When they met, Sanagi gave Kousaka a Shinkansen ticket. He'd heard they were going to go further out than usual, but thought it would still be within the prefecture at best, so this made him nervous.

He was about to pay her for the ticket, but Sanagi plainly denied him.

"This is a present from me, so I don't need money. In exchange, you can't complain no matter what our destination is."

"Got it," Kousaka acknowledged. Then he quietly appended "As long as it's not too dirty."

The two left for their destination. They kept gloves and headphones in their bags in case they were needed, but they were meant to be last resorts. Unless something came up, they didn't intend to take them out.

Kousaka had hardly any memory of the trip. He was desperately trying to not think about anything, leaving him no time to relish the scenery or have a conversation. Sanagi was much the same way, hiding her face and fidgeting the whole time they rode the train.

Indeed, their symptoms were much weaker than usual. But it was akin to your body temperature dropping from 104 to 102, so while it was quantifiably "better," it didn't change that they were serious disorders.

When they got off at Tokyo Station and switched to the Yamanote Line, Kousaka's anxiety peaked. It was terribly crowded in the train, and every time it jolted, he bumped into nearby passengers, which repulsed him like insects were crawling all over his body. Just breathing felt like it contaminated him with the air others were breathing.

His stomach ached, and he felt very nauseous. Something sour was welling up in his throat. He was unsteady on his feet, and could well fall over if he wasn't careful.

But Sanagi was beside him. She held the cuff of Kousaka's coat, desperately resisting her phobia and grinding her teeth. When he became conscious of Sanagi's presence, his stomach pain and nausea slowly retreated. I'm the only one Sanagi has to rely on at this moment. What'll happen if I can't hold myself together?, Kousaka thought to encourage himself.

"Are you okay?", Kousaka asked quietly. "Can you keep going?"

"Yeah. I'm fine," Sanagi answered hoarsely.

"If you can't bear it, tell me right away."

"It's you who looks terrible," Sanagi laughed, acting tough. "If you can't bear it, tell me right away."

"I'll do that." Kousaka laughed, too.

The ride lasted less than 20 minutes, but to paraphrase Einstein, it was twenty minutes of putting your hand on a hot stove. When they got off the train, Kousaka felt exhausted like he'd been trapped in there for two or three hours.

After getting off at Meguro Station and walking west for about 15 minutes, Sanagi stopped.

"We've arrived."

Kousaka looked up. In front of Sanagi was a compact, six-story building. On the building were the words "Meguro Parasitological Museum."

Parasitological Museum?

"Doesn't look like much of a place for me," Kousaka meekly protested.

"You promised you wouldn't complain no matter where it was, right?" Sanagi shifted her head and smiled.

He didn't have the energy left to defy her.

Following after Sanagi, Kousaka entered the museum. In an area resembling a small waiting room was displayed information about and samples of parasites. The two of them started at one end and looked at them in order. There were rows of specimen bottles lined up in glass cases containing various types of parasites, as well as some of the creatures and even organs the parasites inhabited.

Until he actually saw them, Kousaka was concerned that just looking at samples of parasites might make him sick enough to faint. But the parasites in the medicine-soaked bottles looked more like abstract sculptures than insects, so they struck him as surprisingly clean.

Some of the parasites had appearances resembling noodles or vegetables. Hookworms and beef tapeworms were like curly kishimen noodles, roundworms like tangled bean sprouts, Gyrocotylidea like cloud ear mushrooms. Of course, there were a number of grotesque samples that made him want to look away as well: a field mouse with echinococcosis that had a massive tumor on its stomach, the head of a green sea turtle infected with Ozobranchus branchiatus. Kousaka's face reflexively twitched when he saw these, but Sanagi admired them without issue.

Besides Kousaka and Sanagi, there were five other groups of two visiting the museum, and four of the groups were couples. Kousaka had a hard time understanding why that many people would go here for a date. Some of the couples were making a clamor like they came here wanting to see something scary, but others were casually discussing the exhibits and throwing technical terms around.

"Mr. Kousaka, look."

Sanagi spoke, having been looking at the displays silently until then. She was looking at a specimen bottle with a sticker labeled "Diplozoon nipponicum." The caption said "It looks like a single butterfly at a glance, but this special parasite is two worms who met as larvae and became one" - more or less coinciding with what Sanagi had told Kousaka. The founder of Meguro Parasitological Museum, Satoru Kamegai, studied this parasite as his life's work, so it was also like a logo for the museum.

Kousaka looked through the magnifying glass installed in front of the bottle.

"Well?", Sanagi asked from beside him.

"...They're butterflies."

Indeed, they looked like butterflies. White-ish butterflies with small rear wings. They had nearly the same shape as the keychain Sanagi had.

Kousaka squatted in front of the glass case and watched the D. nipponicum samples for some time. Somehow, Kousaka felt like these symbolically-shaped parasites were very nostalgic.

The panel on the second floor featured well-known parasites like Toxoplasma gondii and Echinococcus, and there was also an explanation of Spirometra erinaceieuropaei. According to the explanation, when S. erinaceieuropaei infects a human, it can cause a parasitic disease called sparganosis. The disease's Japanese name contains the term "orphan worm," referring to insects whose larval form has been identified, but not their adult form.

"Strictly speaking, the use of "orphan worm" isn't accurate," Sanagi added from the sidelines. "When S. erinaceieuropaei was first discovered, their adult form was unknown, so they were treated as orphan worms for over thirty years. So the disease's name incorporated this term, and even though the adult form has been found now, it keeps that name for customary reasons."

As usual, she gets so talkative when it comes to parasites, Kousaka thought with a smirk.

Sanagi pointed to the right side of the glass case.

"On the other hand, the adult form of these Sparganum proliferum has gone unfound for over a century, so they're real-deal orphan worms. When they infect humans, they repeatedly split up inside the body to multiply, and invade and destroy all sorts of systems, including the brain. Ultimately, the infected person is completely full of them and dies. There's currently no established treatment, so the fatality rate is 100%. Medicine doesn't work, and they're too numerous to do anything surgical."

Kousaka gulped. "There exist parasites that dangerous?"

"Yeah. Of course, there's only ever been a dozen or so reports worldwide of them infecting humans."

Then the two of them looked at the samples in silence for a while.

"Hey, Sanagi, I just thought something," Kousaka said, still looking at the Sparganum proliferum. "Why would they kill humans? From what I'm hearing, what these things do is like a double suicide. If they kill the host they're inhabiting, they'll go with it, right? Why would they sink the island they live on?"

Sanagi looked toward Kousaka as if to say "that's a good question."

"Parasites aren't always necessarily able to infect who they want. Sometimes they end up lost in a non-definitive host - a host that's not intermediate nor final, and can't even become a standby host. To a parasite, infecting a non-definitive host means forever losing the chance to inhabit their final host. When this happens, most parasites will just die off, but some will stubbornly resist, and in trying to reach a definitive host, move around organs and systems as larvae. In some cases, this can cause symptoms of serious illness. It's a class of disease called larva migrans. When Gnathostoma, which infect freshwater fish, infect a human instead, they can go astray in their body for over a decade."

"It's just trying to get away from the body it wandered into by mistake?"

"I guess that's pretty much it. Even that terrifying Sparganum proliferum should be docile when it infects a definitive host. Because you're right, if they kill their final host, they'll just be going down with it."

Kousaka nodded. Come to think of it, he'd heard Echinococcus was spread from foxes to humans, and was harmless as long as it inhabited foxes.

Sanagi went on talking eloquently. "That said, it's not like parasites will never harm their final hosts, either. For example, beef tapeworms are parasites that infect humans as final hosts, but when these larvae invade the brain and spinal cord, they cause cysticercosis, a very lethal disease to us. And -"

Suddenly, Sanagi's mouth shut. She'd realized the visitors around them had gone silent and were listening to her talk. While some were looking at her like some curious creature, there were others who were genuinely impressed. Sanagi looked around, realized she'd unintentionally been drawing attention to herself, and hurriedly hid behind Kousaka's back.

"...We should get going," she said in a wispy voice.

"Yeah," Kousaka affirmed.

If Sanagi had finished her explanation of cysticercosis that day, the outcome of a later incident might have ended up a little different.

When people ingest beef tapeworm eggs, the eggs incubate in their organs, and become larvae called bladder worms. Bladder worms move through the intestine, and create cysts there. When these cysts form in places like the brain and spinal cord, it causes cysticercosis, but in truth, the symptoms of it almost never appear while the bladder worms are alive.

The problems arise after the bladder worms die. The death of bladder worms in the central nervous system causes a strong tissue reaction. It causes local inflammation and glioma around the cysts, which can result in nerve damage and epileptic fits. At this stage, the death rate from cysticercosis can be as high as 50 percent.

There was an important reason why none other than Kousaka should have had this knowledge. For a layman of parasites like himself, it may have been downright impossible for him to ignore preconceptions and put together the knowledge to arrive at the truth.


Compared to the trip there, the return trip was much easier. After a short rest at a café to get a light meal, they headed home. The two of them chatted idly their entire time on the Shinkansen.

"Come to think of it, I happened to hear once that parasites can cure allergies. Is that true?"

"There have been experimental results showing that. Not only allergies, but they seemed to be effective against autoimmune disorders like ulcerative colitis and Crohn's disease. But naturally, healthiness can't be guaranteed, so using them domestically as cures is probably a long way off."

Kousaka twisted his neck. "How does that work, exactly? Normally, I'd expect the introduction of something foreign like a parasite to cause serious allergies."

"That definitely happens too, of course. But..." Sanagi was silent for a few seconds, like she was unpacking a compressed memory. "In some ways, human immune systems were formed with the assumption of parasites existing. There would be a panic if we found parasites coming out of our bodies now, but just a few decades ago, it was normal to have various parasites. If our immune systems attacked them one by one, the human body would be a constant battlefield, and be torn to shreds in the blink of an eye. So our bodies are built to choose a path of coexistence with relatively-harmless intruders."

"Peaceful coexistence, huh?"

"Right. It has to do with the cells that suppress immunity, called regulatory T cells - depending on the person, there may not be enough of these cells, and immunotolerance won't kick in. As a result, the immune system may excessively attack foreign substances, or even become hostile to your own cells and systems. Broadly speaking, this is what causes allergies and autoimmune diseases. Thus, making the immunosuppressive system work is linked to bettering immunity-related diseases. But apparently, these regulatory T cells are brought about by the existence of "parasites approved by the host." So in essence, the absence of parasites, an extremely clean situation, results in an increase in modern day allergies and autoimmune diseases."

Kousaka thought it over for a bit. "In other words, parasites can cure allergies by cleverly weakening the immune system's defenses?"

"If you break it down, I think that's about correct."

Kind of reminds me of Freud's Eros and Thanatos, Kousaka thought. That was all about how energy which was outward-facing could be turned inward and become self-destructive.

"Still, it's kind of shocking to hear that the human body is "built on the assumption of parasites.""

"Is it really? Isn't intestinal bacteria a clear example of that?"

Kousaka could understand that. Now that she mentioned it, it was true.

While walking down a corridor on the second floor of a train station they got off at to change trains, Kousaka casually looked out the window and over the street in front of the station. The trees were decorated with Christmas lights, and the street was colored by fantastical orange light. As he looked over toward Sanagi, he saw her also staring at the decorations. Her eyes had a complex mix of scorn and envy.

A few dozen minutes after changing to a private railway, they finally saw some familiar streets. They left the station and took in the fresh air again. The night sky was pretty and clear, and you could easily see the half-waned moon.

"Seems we made it back okay," Sanagi said emotionally.

"Somehow," Kousaka said. "That was pretty rough for our first training."

While walking through the silent residential district, Sanagi came to a sudden halt. She was looking at a children's park. A cramped one that didn't seem suitable for catch or tag or anything. Sanagi stepped toward it without hesitation. Kousaka followed.

Seemingly unused for a long while, there was a staggering amount of snow piled up in the park. Each step had their feet sinking into the snow up to the ankles. It was snow that solidified easily, so by stomping on the snow piles in your path to make footholds as you went, you could avoid getting snow in your shoes.

Reaching a bluish-green jungle gym, Sanagi went up without hesitation. She sat at the top, went "it's cold, it's cold" as she warmed her hands with her breath, then looked down at Kousaka below and grinned proudly.

Kousaka timidly touched the jungle gym. And brushing away snow to avoid slipping off, he carefully climbed up to sit next to Sanagi.

He hadn't climbed a jungle gym since grade school. The two were silent for a while, enjoying the nostalgic yet fresh sensation. Just by having a view a mere two or three meters higher, the world looked somehow different from usual. The snow in the park absorbed the moonlight and glowed a pale white.

After some time, Sanagi broke the silence.

"Mr. Kousaka, do you remember the Diplozoon nipponicum I told you about earlier?"

"Of course I remember. Looks like a butterfly, fateful love at first sight, lifelong copulation, love is blind, two peas in a pod?"

"Fantastic." Sanagi brought her hands together and smiled. Then she continued. "Hey, Mr. Kousaka, have you ever thought about this?"

Maybe my whole life, I won't have anyone to call my partner.

Maybe I'll die without ever being in love with someone.

Maybe when I die, there'll be no one to shed tears for me.

"I'm not D. nipponicum, so sometimes before I fall asleep, I think about things like that," Sanagi said casually without any emotion. "Do you understand those feelings, Mr. Kousaka?"

Kousaka nodded deeply. "I'm always thinking about that kind of thing. When I'm walking around and see a perfectly happy-looking married couple, I really think about it. "That's probably something I'll never have all my life." It makes me unbearably sad to think so." Then he took a breath and made an addition. "But I don't think you need to think about things like that, Sanagi. You're still much younger than me, and clever, and honestly, good-looking. You have plenty of things to make up for your faults. I'm sure there's no reason to get pessimistic so soon."

Sanagi slowly shook her head. "Mr. Kousaka, you can only say that because you don't know me very well."

"You might be right. But it's a mistake to think you're the one who knows yourself best. There are things you overlook about yourself. Sometimes, what other people see might be closer to the truth."

"...I guess so. It'd be nice if that were true."

Sanagi's eyes narrowed sadly, and she opened her mouth to say something, but rethought it and pursed her lips. Then she slowly sat up.

"We should go home soon. I'm getting pretty chilly."

"Let's do that." Kousaka got up, too.

After leaving the park, the two were completely silent. Ultimately, it came time to part without them having said another word to each other. Kousaka began - "Well," - to say goodbye, but Sanagi interrupted him.

"Um, when you do something, I think it's best to have a clear goal in mind."

It took Kousaka about five seconds to realize she was talking about trying to conquer the obstacles posed by their compulsions.

"So, how does this sound? By Christmas Eve, I'll be able to walk around town without people's gazes bothering me. Mr. Kousaka, you'll be able to hold hands with someone without dirtiness bothering you. If we achieve those goals, then on Christmas Eve, we'll hold hands and walk by the Christmas lights outside the station, then have a modest celebration."

"Sounds like fun."
"Then let's promise."

With that, Sanagi turned and quickly left.

After getting home, without any particular intention, Kousaka looked up Meguro Parasitological Museum. And a surprising fact came to light. It seemed Meguro Parasitological Museum was a famous date destination in the area. That's why there had been so many couples.


Chapter 5: Winter Wormderland

The two came to have outings together at a fixed time every day. Sanagi would visit the room like usual, they'd first spend about thirty minutes idling together to settle down, then make preparations and leave, walk around for an hour, return to the apartment, and calm their high-strung feelings in whatever ways they wanted.

At the end of the day, they gauged the results of their training. Sanagi would test how many seconds she could look Kousaka in the eye, and Kousaka would test how many seconds he could hold Sanagi's hand.

Kousaka could feel himself getting better with each passing day. As usual, he couldn't ride the train by himself, but if he went with Sanagi, he could even do a simple restaurant visit. Though it was slow going, he washed his hands less frequently, spent less time cleaning, and the smell of disinfectant in the room weakened.

Upon seeing that Kousaka's germaphobia had gotten better, Sanagi started taking him to feed wild animals. Swans at the lake, stray cats in the park, pigeons in the station plaza, seagulls on the coast, eventually even crows at the dump - Sanagi fed them all without discrimination. Kousaka watched her from a bit of a distance.

Kousaka asked her what exactly she liked about animals, and Sanagi had a somewhat surprising answer.

"I read in a book a long time ago that animals don't have a sense of past and future; to them, there's only the present. So as much pain as they experience, even if it accumulates as an experience, the pain itself doesn't accumulate. So their first pain and their thousandth pain can only be recognized as "my current pain." Thanks to that, they can't have hope, but can't fall into despair, and just seem to stay in that peaceful state. A certain philosopher once called it "total investment in the present"... but I look up to that way of living animals have."

"That's kind of complicated. Can't it just be like "cats are cute, so I like them"?"

"Of course cats are cute," Sanagi said as if wounded. "If I could be anything, I'd want to be a cat. Also, I'd like wings like a bird."

"You want to be a winged cat?"

"That wouldn't be a cat," Sanagi firmly denied.

As the two walked around town, they made various discoveries. The sights Kousaka always passed by looking straight ahead, with Sanagi beside him, became a source of imagination: "I wonder how this world looks to her eyes?" It was like getting a fresh set of sensory organs. Like having a camera equipped with a brand new lens, everything became a subject for reevaluation.

Perhaps Sanagi was feeling the same way. One day, she looked into the distance and mumbled something.

"Walking through town alone and walking through town together are completely different, huh."

Sanagi painted the colors Kousaka left unpainted, and Kousaka painted the colors Sanagi left unpainted, completing each other's worlds. By doing this, the world stood out more clearly.

It was tastier eating together than alone. It was more fun going together than alone. It was more beautiful looking together than alone. Something so obvious to most people, it didn't merit saying. But to Kousaka and Sanagi, it was a major discovery that shook their view of life. Happiness was resonance.

Now, they felt like they could understand the reason people came together to live.

Kousaka hadn't forgotten Izumi's warning. He obeyed his command to "keep things as they are," trying to keep a reasonable distance from Sanagi to avoid being too intimate with her. Each step she took toward him, he backed away, and if she backed away, he stepped toward. It was like a dance.

But even if it wasn't their intention, the distance between them certainly lessened. It was just natural. People who spent so much time together, shared their worries, and shared their worlds couldn't possibly not advance their relationship.

Unknowingly, Kousaka had reached a point of no return. Now, they were barely within the realm of friends, but it seemed only a matter of time before a sudden beat made them lose balance and fall forward.

And soon that time arrived. The night of December 20th, a night of falling sleet.

Kousaka had dozed off in his chair. It wasn't that he was tired, or sleep-deprived. He just liked sleeping with Sanagi around.

It had become a daily routine. When he nodded off while Sanagi read, he could have good dreams. There was no distinct story, just a fragmented patchwork of images, and he couldn't remember a single concrete thing after waking up, yet there was still an echo of happiness. Those kinds of dreams.

When he woke up that day, Sanagi's face was in front of him.

Kousaka jumped a few centimeters in surprise, but she showed even more of a reaction. The instant he opened his eyes, Sanagi jumped back in a flurry. A reaction like a child secretly doing something bad being shouted at from behind.

And they met eyes. Sanagi was surprised - but it was directed at something other than Kousaka suddenly waking up.

"Good morning."

Kousaka smiled at Sanagi. His smile said "I'll act like I didn't see anything."

But Sanagi didn't respond. She sat on the edge of the bed, stared at a balled fist on her lap, and fought an internal confusion. Her eyes, usually listlessly droopy, were wide open, and her ever-tightly-pursed lips were half-open.

Soon, she came back to her senses and looked up. She took a deep breath, then spoke in a hoarse voice.

"I'm sorry."

Kousaka found himself confused by her expression of agony, like a murder had just been discovered. Just afterward, he realized with a delay what Sanagi had been trying to do. He realized the angle of her face when he woke up to it, and the angle at which she'd kissed him through a face mask, were a perfect match.

"That's too overblown. I don't mind that much," Kousaka said. "And I didn't scratch you this time."

"No," Sanagi said, shaking her head forcefully. "I was just about to do something there was no coming back from."

With that, she held her knees on the bed and moped into them.

No coming back? Kousaka wracked his brain. There was only one thing he could think of. She was probably apologizing for nearly making him break the "don't cross the line" rule Izumi had issued.

Indeed, it was a close call. But even so, her reaction seemed too overdramatic. Even if it was through a mask, she had done effectively the same thing once already. He couldn't help but feel "what does that matter now?"

However, Sanagi's next words gave him a shock.

"If we keep staying together like this, I think I'll kill you someday, Mr. Kousaka."

She kept her eyes off Kousaka, smiling lonesomely.

Wiping the tears from her eyes, Sanagi stood up.

"So, I won't come here anymore."

Saying nothing more, she left the room with no hesitation.

By the time Kousaka recovered from his confusion to go after her and leave the apartment, Sanagi was nowhere to be found.

Heavy sleet poured down on the town.

And thus, Kousaka was alone again.


A few days passed.

Kousaka knew that coming to an answer wouldn't make Sanagi come back, but he couldn't help thinking about why she'd vanished.

He didn't think he'd made any huge mistake. In fact, for the past ten days, their relationship had been very favorable. He was confident about that. She was enjoying their time together deep down. That much was certain.

It's not that she left because she hates me, Kousaka figured. However... Like she said, I don't know much about her. I was only under the impression I did.

Yet now he could understand somewhat. There was "something" more devastating than scopophobia residing in her, and it prevented interaction with others. While he had no proof, he was instinctively sure of that. Scopophobia was only one symptom which stemmed from this.

It was extremely disappointing, but when he considered how the six people asked to do this job before him had failed, it felt only natural that Sanagi ran from him. Perhaps this was an unwinnable game from the start.

There was just one thing that didn't sit with him. What did she mean by "I think I'll kill you someday"? Should I interpret it as an exaggerated expression for troubling me, or interpret it literally? ...No, I should stop. Thinking about things that are done and gone doesn't do any good.

Kousaka's life went back to how it was before meeting Sanagi. At first, he felt like he had nothing to do spending the afternoon alone, but he quickly got used to it. And he wouldn't easily forget the living rituals he'd kept up for over five years. He thoroughly cleaned the room, cleaned up Sanagi's bloodstains, and took repeated showers to drive off the feeling of Sanagi.


December 24th, 4 PM. Less than an hour remained before the activation of Kousaka's creation, SilentNight. It was unclear how many devices had been infected, but it couldn't be less than a few thousand as a low estimate. Because the malware he'd created was quite distinct from the mobile malware that had been made prior.

Kousaka, the author, was not very aware of it himself, but SilentNight was extremely revolutionary mobile malware. There did exist prior malware that disabled the communication functions of phones. SilentMutter and Radiocutter discovered in 2009, for example. But at any rate, of the mobile malware recognized in 2011, the majority were trojans due to technical hurdles. SilentNight, meanwhile, was a mobile worm that infected the network and could self-replicate, so its ability to diffuse was incomparable to previous mobile malware. And at least currently, there were no anti-virus programs that detected this malware.

A powerful virus that struck in 1999, Melissa, was said to have caused over 80 million US dollars in damages. Furthermore, a virus that surfaced the next year, Loveletter, was said to cost over a few billion dollars. Even this malware created by individuals could deal an unheard-of blow to the world if it worked its way into the gears. If all went well, even if it didn't shake the world, SilentNight might get a lot of people's attention for two or three days.

But Kousaka didn't much feel like watching it happen. Though creating malware had been what he lived for, now, it just felt empty. Kousaka himself didn't know whether that was due to Sanagi or not.

I'll turn myself in before the date changes, Kousaka silently decided. He wasn't accounting for the fact that turning himself in might result in a lighter sentence than Izumi doing it for him. He simply felt it was just right.

Upon getting outfitted and standing at the door, the intercom sounded. He knew it wasn't Sanagi. He figured it was probably Izumi, but Kousaka's intuition was also wrong there.

Standing at the door was a deliveryman. The man bluntly handed him a pen and voucher. Kousaka signed, and the man handed him a paper bag and quickly left.

He returned to the living room to open the bag. Inside was a wine-red scarf. When he unfurled the folded-up scarf, something fell out. It was stationery with a simple design and an envelope. The contents of the envelope were sticking out slightly after the fall: a stack of bills.

Kousaka picked up the stationery and stuffed it in his coat pocket. He didn't stop to count the bills. He knew how much it was, and the reason he had been sent it.

Sanagi probably took half the payment from Kousaka as a condition for becoming friends because she wanted to be on equal footing with him. She absolutely didn't want him to feel like he was working for money. Now that their relationship had failed, there was no longer a need to maintain that equality.

Kousaka unplugged his smartphone from the charger it was always plugged into, stuffed the scarf in his bag, and left the room. He was headed to the police station. He didn't know why, but he felt that to turn himself in, he should do so by going there directly instead of calling in.

He didn't wear gloves or a mask. It was a meager punishment for himself.

On the way, Kousaka took the stationery out of his pocket and read it.

"I must have startled you suddenly leaving the way I did. I'm really sorry. I really would like to explain myself, but I can't say anything. Because as many words as I tried to use, it would probably only deepen your confusion. One thing I can say for sure is that you have no responsibility, and the problem lies entirely with me. I was wrong to have a desire that was totally beyond me."

She had neat writing for her age. Her writing was also different from her usual informal tone. But strangely, nothing felt wrong about it. He felt that the words she wrote in the letter were closer to Sanagi's inner self than the words she spoke.

Kousaka looked to the second sheet of stationery.

"Mr. Kousaka, I liked spending time in your room, not doing anything, just spacing out. It was my first time experiencing such peaceful feelings since I was born. I think it was thanks to having someone I liked there. Thank you for the wonderful time."

Following blank space like a period of silence, Kousaka looked at the third sheet.

"It's not exactly a repayment, but I've sent you a scarf I knitted. Yes, this is the "girly hobby" I was hiding. If it doesn't please you, I won't mind if you throw it away. To tell the truth, I simply wanted to try giving someone a gift once."

The fourth sheet.

"I've directly asked Izumi to let you free, Mr. Kousaka. He's always incredibly indulgent to me, so I'm sure he'll do as I said. ...I actually planned to only send you this part, but I've gone on and on writing excess things. Sorry."

And this is how she wrapped up her letter.

"This will be my final contact to you, Mr. Kousaka. It's fine to completely wipe your mind of me. Goodbye."

At about the same time Kousaka finished reading the letter, he arrived at the police station. Kousaka stood there. The clock inside was just striking 5 PM.

He put away the stationery in his pocket, took out the scarf from his bag, and held it in front of him. It was a neatly-knit Aran-patterned scarf, easily mistakable for a commercial product.

Kousaka wore the scarf. He did this, knowing it was handmade. He found it strange himself. He who hated the "hand-cooked," "handwritten," "handmade" - anything touched by a hand - should have normally been disgusted by the gift, even if Sanagi had made it for him. There was an inconsistency that couldn't be explained away with "it's cold enough that I need the protection."

Standing outside the station, Kousaka buried his face in the scarf, staring at shimmering red lamps.

He wasn't sure how long he did it for.

All of a sudden, it occurred to him how he was hopelessly in love with Hijiri Sanagi.

It was his first love, at age 27.

And she was a 17-year-old girl.

But he couldn't see it as shameful. As inherently irregular people in irregular circumstances, they had an irregular love. There was nothing strange about that.

He turned his back to the police station. He no longer felt like turning himself in.

His actions afterward were rapid. Kousaka turned on his smartphone for the first time in days. He called Sanagi's number, but the call sound was cut off after one ring. It was a strange way for a call to cut off. He tried again and again, to the same result. It didn't have the feeling of her phone being off or her being somewhere without reception. Was she rejecting calls from his number?

Just then, he hit upon a possibility. Maybe this is the fault of SilentNight. Maybe it far exceeded my expectations and spread massively, eventually infecting even Sanagi's phone. Considering it now, it wasn't implausible.

Kousaka was at a loss. If he was right, then she'd lost communication just a few minutes ago. Even if he tried to go meet her in person, he didn't know Sanagi's address. Would he have to wait out the two days until the worm's effects stopped? He shook his head; no, that won't do. He felt like he had to tell Sanagi today, or he'd lose the chance to do so ever again. There was no time to delay it any longer. But where could he look to find her? He frantically searched his head, but had not a single idea.

How ironic, Kousaka laughed. The worm I made to cause couples trouble had come around to bite me. So this is what "a curse is always repaid" means.

He felt something cold on his cheek, and looked up. Had it started to snow? He held up his hand and waited for snow to fall into it. When he did, he suddenly wondered why he wasn't wearing gloves. From there, his mind jumped from one thing to another. Gloves, training, holding hands, Sanagi's hand, outside the station, Christmas lights, Christmas Eve.

"So, how does this sound? By Christmas Eve, I'll be able to walk around town without people's gazes bothering me. Mr. Kousaka, you'll be able to hold hands with someone without dirtiness bothering you. If we achieve those goals, then on Christmas Eve, we'll hold hands and walk by the Christmas lights outside the station, then have a modest celebration."

If she's anywhere, it has to be there, Kousaka concluded.

He raced to the station and lept onto the train just before it left. There were a few empty seats, but he didn't take them, and stood by the wall catching his breath. He took out his smartphone, and to check the status of the worm's infection, checked if anyone had mentioned a new worm online in the past hour. From what he could see, there were only five or six people saying their phones had suddenly lost communication. Kousaka almost felt relief seeing this, but shortly realized his stupidity. Those affected by this worm, unless they had another device on hand, wouldn't be able to go online and say anything. Using the internet to check for people who'd lost internet was like counting casualties with a roll call.

He gave up on checking the state of the infection and put the phone back in his pocket. It would probably still be some time before damages became evident.

After getting off the train and going through the ticket gate, a middle-aged man called to him. "Sorry for the rude request, but could you lend me your cellphone?", he said. "There's someone I want to contact ASAP, but it seems my smartphone suddenly broke earlier."

"I can't make calls or send emails, but I can check my address book. I thought I'd just use a public phone, but as you can see..."

Kousaka saw a strange sight where the man pointed.

Outside three phone booths some distance from the ticket gate, there were long snaking lines. At the front was someone looking at a smartphone screen and pressing the buttons on the public phone. They were probably all victims of the worm.

Kousaka gulped. This may perhaps be more serious than I anticipated.

Though it was a race against time, Kousaka lent the man his phone. Not knowing that this generous young man was in reality the cause of all this commotion, he bowed his head deeply and thanked him.

While the man made his call, Kousaka tried to think about means of contacting Sanagi. Then he suddenly realized. There was no need to make contact. If Sanagi still felt like meeting me, she'll definitely appear outside the station tonight. That was what she promised. On the other hand, if she didn't want that, then it would be pointless even if I could call her. My primary worry right now is that, regardless of whether Sanagi appears, I'll fail to find her.

Kousaka saw a station employee put a signboard outside the ticket gate, and people started to crowd around it. The man finally finished his call, returned the smartphone to Kousaka, thanked him, and left. Kousaka resisted the urge to disinfect the phone and stuck it in his pocket. And he left the building to head to the plaza. If Sanagi did appear, that's the place she'd choose.

It seemed like there were many lonely young people in the plaza. Surely not all of them were, but no doubt at least some percentage of them had lost their means of communication due to the worm and couldn't meet who they were intending to. People smoking cigarettes with displeasure and looking into the distance, people sitting on benches and looking around constantly, restless people walking around the plaza. The scene reminded him of a time before cellphones were widespread.

Kousaka sat on a bench beside the clock, and kept watching the people leaving the station. He sharpened his senses so he wouldn't miss a single person who went in or out of the station.

But an hour, two hours passed with no sign of Sanagi. Every time he saw a woman with bright, short hair, he looked up hopefully, but they were all the wrong person.

The snow picked up, and the people who filled the plaza gradually lessened in number. Before he knew it, there were enough left to count on one hand. Those who came in and out of the station became sparse, and it was no longer necessary to focus his senses.

And a total of three hours passed.

Maybe it's pointless to wait any longer, he thought.

That promise has long since lost its effect.

He sighed and looked up at the night sky. He was freezing all over; below his knees especially, he was unbelievably cold. But physical coldness was no big issue. A warmth in his chest that had felt like part of him went out, and a heavy chill filled the space. The faint heat that remained only seemed to reinforce the cold.

Ah, so this is what loneliness feels like, Kousaka finally realized at the ripe age of 27. The scales had fallen from his eyes. Until now, he had been faintly aware of the shapes of love and loneliness, but decided they were things irrelevant to him. To think the day would come when he could feel them like this. Maybe the kiss Sanagi gave me that day rewrote some of my data, Kousaka thought.

The clock rang out, informing him it was 9 PM. Less than an hour until the Christmas lights turned off.

At that point, there was nothing keeping Kousaka there but stubbornness. Surely Sanagi isn't going to appear at this point, he thought, starting to discard his hopes - and in a way, he was correct.

After the bell finished ringing, Kousaka looked all around. Almost everyone in the plaza had vanished; all that was left was himself, and a single girl. She looked like a docile girl in a quiet outfit. She buried her face in a scarf to endure the cold, keeping her head down. Likely from doing that for a long time, her head and shoulders were covered with white snow.

Maybe she was another person who failed to meet the one she loved. That thought filled Kousaka with feelings of regret. Now, he could understand her feelings to a painful degree.

I want to apologize to her, Kousaka thought. Say I'm the one who caused all this trouble, I was jealous of all the couples and created a worm that made all this happen. Of course, she probably wouldn't believe him if he said that. She'd just think he was nuts. But his judgement had long since gone numb from the cold and despair.

Kousaka got up from the bench and walked toward the girl. All his muscles were stiff, so he walked awkwardly like a marionette.

"Um, excuse me."

The girl looked up when he spoke to her.

And she smiled.

Just like that, Kousaka was unable to speak a word.

He was so shocked, he forgot to breathe for a while. It felt like all the energy had left his body.

"I was waiting to see when you'd notice," the girl said.

"...That's unfair," Kousaka said at length. "You look way too different. There's no way I could tell."

"But there's no point in changing if I don't change that much, right?"

Sanagi slowly stood up and swept the snow off her hair and coat.

Perhaps Sanagi had been there for a long time now. Kousaka simply overlooked her, and she was in sight the whole time. Not like he had something wrong with his eyes, though. Nine out of ten people would probably make the same mistake.

When Kousaka imagined Hijiri Sanagi, he first pictured her dyed hair. Then her unrefined headphones, her short skirt, her blue earring. The girl in front of him met none of those requirements. Her hair was black, she wasn't wearing headphones, her skirt was an average length. The earring was still there, but you couldn't tell that without coming up close.

"I was about to give up and assume you wouldn't come. Sheesh, Sanagi, you're mean," Kousaka said in amazement.

"I was right by you. It's your fault for not noticing, Mr. Kousaka."

"You're one to talk." Kousaka furrowed his brow. "Did you notice me from the start?"

"Yeah. Because of that scarf." Sanagi looked at Kousaka's neck. "I knew instantly. Glad to see you actually using it."

"Right. Today was especially cold, so...", Kousaka said with some embarrassment. "That aside, does your natural hair color mean you intend to go back to school?"

"Well, there's that."
"There's another reason?"

"Err..." Sanagi's gaze turned down diagonally, and she spoke while fiddling with her hair damp from the snow. "I figured you liked this kind of diligent feel, so..."

Sanagi laughed like it was a joke, but Kousaka didn't laugh.

The chilled core of his body warmed up like a flame had been lit.

A moment later, Kousaka was hugging Sanagi.

"Huh?", Sanagi yelped in surprise.

"...Does it feel okay?", Sanagi asked with concern from within his arms.

"To tell the truth, it doesn't really," Kousaka said, stroking her head affectionately. "But for some reason, I can forgive being made dirty by you."

"...You're rude," Sanagi said with a laugh, and brought her arms around his back.


In the seven days up to the new year, Kousaka and Sanagi had the most peaceful and fulfilling time of their lives. Everything they'd lost in their lives prior, that they couldn't get, that they'd given up on, they took back one at a time. It was happiness that to most people wasn't rare, just shabby and trivial, but to the two of them it was like a pipe dream. Just holding hands, just being shoulder to shoulder, just looking each other in the eye, were major events in their personal histories.

In these seven days, Kousaka never reached out toward Sanagi. Not out of any duty to Izumi, or because he found her body impure, or because he lacked the courage to cross that line. He simply wanted to treat Sanagi dearly. He could afford to wait until she was a proper age to think about such things.

Perhaps sensing that consideration, Sanagi also refrained from excessive touching and showing skin, seemingly cautious not to stimulate him more than necessary. Kousaka was very grateful for her cooperative attitude. Even with the difference in their ages, self-control was something that could very quickly crumble if poked too much.

Truthfully, in the last few days of the year, there was quite a panic over the mobile worm that wreaked havoc from Christmas Eve to Christmas night. The first mobile worm in the world to spread on such a large scale, SilentNight made a small etching in the history of malware. But Kousaka, who didn't look at any form of news in those seven days after Christmas, had no way of knowing that.

At this point, nothing mattered to him. He felt like there was nothing but Sanagi worth giving his attention to.

Later, he'd look back and recall - maybe I knew somewhere in my heart that this was my first and last opportunity, so I could spend every second carefully and without regrets.

Kousaka was so convinced that these happy days wouldn't last long, it was as if he'd seen the future with his own eyes.

Maybe it was just a feeling worming its way through his mind.

He chose not to ask Sanagi about the meaning of "I think I'll kill you someday." He felt having her reveal her secret would only shorten their already-short deferment.

Even if postponing the conclusion proved to be what caused Sanagi to indeed kill him, he wouldn't mind that. If she wants to kill me, I'll let her do as she likes, Kousaka thought to himself. Because if Sanagi went away, his life would no longer have meaning.

Izumi appeared in the afternoon on January 1st. After the two paid a visit to a temple for the new year, they didn't do anything and just dozed off in the room with the curtains closed. Just as Kousaka was a moment from falling asleep, he was pulled back to reality by the sound of the intercom.

He gently put Sanagi, sleeping soundly on his lap, on the bed without waking her, then answered his guest. Even after seeing Izumi at the door, he was hardly fazed.

"I thought it was about time for you to come," Kousaka said, his eyes squinting from the light.

"Is Hijiri Sanagi there?", Izumi asked. Because of the backlight, Kousaka couldn't quite read his expression.

"She is. She's asleep, but should I wake her up?"
"Yeah. Sorry, but do that."

Kousaka returned to the room and gently shook Sanagi's shoulders. "Izumi's calling," he said, and she quickly opened her eyes and got up.

The two did as Izumi told them to, and got in the back seat of a car parked outside the apartment. It was a gray car that left little impression and could easily be lost if it were parked in a large parking lot. The heater was on inside, and the seats had a faint aromatic smell.

For a while after the drive started, the three didn't say a word. They got on the highway, and while stopped at a light, Izumi finally spoke.

"Kengo Kousaka. I'm going to have to tell you a somewhat shocking fact."

"Izumi," Sanagi interrupted. "...Don't."

But Izumi ignored her, and continued.

"There's a new kind of parasite residing in your head. It doesn't have any official name yet, so we just call it the "worm." To spare you the tedious explanations, it's that "worm" to blame for you not being suited for society."

He thought it must be some kind of joke.

Some kind of in-joke that only made sense to Izumi and Sanagi.

But looking at Sanagi's expression, it was very clear that it was no joke.

Her lips trembled, and with a face turned pale, she hung her head.

As if she were deeply ashamed that Kousaka had heard this.

"And this "worm" is in Hijiri Sanagi's head, too," Izumi continued. "The worm in your head and the worm in Hijiri Sanagi's head are calling to each other. You might think Hijiri Sanagi's your fateful partner, but that feeling's been created by the worm. What you have is nothing more than a puppet love."

Izumi's expression, seen through the back mirror, looked completely serious.

Kousaka looked toward Sanagi, seeking words of denial.

But all that came out of her mouth was:

"...I'm sorry for deceiving you."


Chapter 6: So Good It Bugs Me

The car stopped outside a medical clinic on the outskirts of town. The trip felt like about 15 minutes, but maybe having so much to think about numbed Kousaka's sense of time, and it was really several times longer. Or maybe the opposite, and it was less than half that.

At any rate, they surely hadn't traveled too much of a distance, but in that span of minutes or dozens of minutes, the scenery changed completely. It was white as far as the eye could see.

The area was surrounded by mountains, and the clinic was the only building within view. A sign marking a bus stop stood out on the roadside, and next to it were two pathetically old wood seats. The sign and the seats were covered with thick snow, so a bus driver would be liable to overlook it. Suffice to say, it was a cold place.

The car stopped, and was enveloped with silence. After a breath, Izumi opened the door and got out of the car. Kousaka and Sanagi followed. When their feet touched the ground, there was a crunching feeling of stepping on snow. Only the front entrance had been plowed, so most of the large parking lot had snow piled up high enough for your ankles to sink in.

The clinic was a tidy but melancholy-feeling building. The outer wall was milk white as if intentionally trying to blend in with the snow, so its shape was fuzzy from a distance. The numerous icicles hanging from the roof were over a meter long at longest, and looked ready to fall from their own weight any moment.

On the wall by the entrance was a sign reading "Urizane Clinic." Through the door was a cramped waiting room with three brown sofas in a row. The fluorescent lighting's life seemed almost up, as the room was dim, and the linoleum floors with a slippery glow were an impure greenish color, giving the impression they were growing mold. In the corner was a decorative plant that was so tall, it really didn't mesh with the small room.

There were three patients in the waiting room, all old people. They were talking about something quietly, and looked toward Kousaka and the others when they entered, but quickly returned to their conversation.

A women in her thirties with a face like a Noh mask operated the reception desk. She bowed her head lightly when she saw Izumi, then as if that were the end of that, lowered her head and returned to work.

Izumi stopped outside the examining room, and urged Kousaka to go inside.

"Urizane has something to talk to you about," Izumi informed him. "We'll be out in the waiting room. Come right back once you're done."

Kousaka nodded, then looked to Sanagi. It seemed she was about to look him in the eye, then she averted her gaze and headed to the waiting room, leaving Izumi behind.

Kousaka knocked on the door, and heard a voice inside say "Come in."

He opened the door and entered the examining room. At a desk left from the entrance sat an aging man who looked like a doctor. His short-trimmed hair was pure white, and his eyebrows and thick mustache were similarly so. On his brow was a deep wrinkle like a scar from something. He must be Director Urizane, Kousaka guessed.

Urizane looked up from the desk and turned around. His revolving chair creaked as he moved.

"Take a seat, please."

Kousaka sat down in the patient's seat.

Urizane looked all over Kousaka's body as if appraising him. At the time, Kousaka didn't know that this old man was Sanagi's grandfather, so he didn't think deeply about what those looks meant.

"How much have you heard?", Urizane asked.

Kousaka recalled the conversation in the car. "There's a new kind of parasite in my head, and that "worm" is making me fall in love and become unfit for society. That's it."

"Hmm." Urizane stroked his mustache with a finger. "Well then, where shall I begin?" He leaned back in his chair and sighed. "Kousaka, was it? Just how seriously are you taking this? This nonsense about an unknown parasite in your head, exerting influence even over its human host's decisions."

"...To tell the truth, I'm still only half-believing."

Urizane nodded. "That you would be. It's the perfectly natural response."

"Although," Kousaka appended, "I did hear from Sanagi that certain kinds of parasites can alter people's actions. And so it doesn't seem impossible that there's a parasite that can influence a person's decisions... But to tell me it explains why I've never fit into society sounds so good on paper, it bugs me. I'm hesitant to believe it..."

Urizane interrupted him.

"No, this is not something so good it would bug you. It's so bad it should bug you."

He pointed to a folded sheet of paper. It was a newspaper clipping dated July 20th of last year with the title:

Suicides at Hospital: Doctor and Patient Go Out Together?

"If things proceed like this, you may be walking the same road as them."

Next, Urizane took some documents out of a drawer and handed them to Kousaka.

"Just before the suicides, the doctor mentioned in that article sent me an email. There was no subject or contents, just a single text file attached. The file was a log of all email exchanges between the two from when they met up to their double suicide. Read those, and you should understand most things about the "worm.""

Kousaka looked down and read the first of the documents.


Sent: 06/10/2011 Subject: I'm sorry about the other day

It's Izumi. During the examination the other day, I'm sorry for getting incoherent, failing to explain the situation well and confusing you, doctor. I thought I had gotten together everything I needed to say in advance, but when it came time to say it to you, I drew a blank. I can't promise that this definitely won't happen again, so I decided to send an email explaining it. I think this will be more reliable and faster than telling you in person, so...

What I was trying to explain last time were the circumstances by which I came to learn your name, Dr. Kanroji. (I'm sure you thought I was a strange patient for bringing up such an old paper out of the blue. Truly, I'm very sorry.) Thinking about it now, if I'd just explained it chronologically, it would surely be a lot easier to understand. I'm really sorry for being so clumsy... I'll learn from my mistake and try to properly tell you the events in the order they happened. It will be a little long, so please forgive me.

At first, I had the symptoms of a headache. I remember it to be in the middle of April.

The headache lasted nearly half a month. I've always had migraines, but the pain had not been this long-lasting before. Previously, I could take medicine and it would heal in two or three days.

That said, I did not consider it very serious at the time. I thought it may be the result of stress, or hay fever acting up. In truth, the headache itself was not such a big deal. After half a month, the pain began to lessen, until finally it went away completely. I was relieved that it was a temporary affliction after all.

The problems came after that. A while after my headache was cured, I realized I was having strange delusions.

I work as a temporary employee at town hall, and normally commute there by driving. One day, I was headed to work as usual, but after passing through a normal intersection, I was suddenly struck with an incredible sense of terror. I quickly hit the brakes, parked on the side of the road, and looked behind myself.

A possibility crossed my mind: "Might I have just run someone over?" Of course, if that had really happened, there would have been a strong impact to the car. No matter how much I was spacing out, I would have known that clearly. Yet I couldn't help but get out of the car and check. Naturally, there was no damage to the car, and there was no person collapsed and bloody on the road I'd driven past. But still, that thick terror persisted in me.

Starting then, whenever I was doing anything, I would be tormented by the fear that I had unconsciously caused harm to someone else. For instance, while going down stairs at a train station, I would become anxious that I unknowingly pushed someone down them. When working, I would be anxious that I had made some massive error and caused everyone trouble. While shopping, I would be anxious that I was unknowingly shoplifting. After meeting someone, I would be anxious I had said something that hurt them. It was fine when it was something that I could check then and there, but in the case of "what if I ran someone over," I couldn't relax until I'd seen the newspaper the next day. It was like that headache that lasted half a month had driven me mad.

I gradually came to find leaving the house troublesome. Scared of harming them, I kept people distant, and became a loner. I could feel peaceful only when I was all by myself at home, sitting still.

I was aware that it was a type of obsessive-compulsive disorder called blaptophobia. And I did have the knowledge that obsessive-compulsive disorders have little hope of being cured naturally. ...Regardless, I was strongly opposed to seeing a psychiatrist. Perhaps I didn't want to admit I was mentally ill. Until then, I had thought of myself as a strong woman.

However, I couldn't stay like that forever. My blaptophobia worsened by the day, and it began to interfere with normal life. So I decided to make up the story "I'm afflicted with chronic headaches, and it's caused me to become overly nervous" to create a reason to go to the hospital, first having a general physician look at me. If they recommended me a psychiatrist, then I intended to obediently go along with that.

However, my test results revealed an unexpected truth. It appeared my blaptophobia was highly likely to be not purely a mental illness, but resulting from an organic alteration in my brain. Unbelievable, there was a parasite in my brain, and that worm was creating a focus infection on it.

I was relieved. It sounds strange that I was relieved to learn there was a parasite in my brain, but I think I was pleased with how easy it was to understand. Thinking that simply removing the parasite could free me from my irrational fears, my heart was cleared up at once.

However - and this is where the story gets increasingly strange - once it came time to undergo treatment, I was hit with an unidentifiable anxiety. It differed in nature from the delusions of hurting others I'd been having; it was a completely baseless feeling that came down upon me. I don't know why, but I had a sudden premonition that if I went through with this treatment and expelled the parasite, I would regret it.

I provided a suitable excuse and fled the hospital. And I never went back there again. What's wrong with you?, I thought to my own self. Yet strangely, I didn't feel like I had done the wrong thing. I think my head was filled with relief from escaping the terror that stood before me.

However, a month afterward, my doubts began to swell. What indeed was the cause of that unidentifiable anxiety? Why had I done such a thing, volunteering my body to protect a parasite? I had been optimistic, thinking that later I could sort out my feelings and the reason would become clear, but the reality was that the mystery deepened by the day. It was as if at that time, I was no longer myself...

Suddenly, I recalled an article I read in a magazine about a year prior. It stated that certain types of parasitic organisms could have effects on humans' personalities and actions.

I searched my memories and dug up that article, and read it over and over again. And after reading related articles and citations, I arrived at the "next" conclusion, so to speak.

My brain was already under the parasite's control.

People may laugh it off as a foolish delusion. In fact, it is the mad idea of a sick person. It's not all that different from a patient with schizophrenia thinking they're being attacked and controlled by radio waves. If my brain has already been eaten into by a parasite, then perhaps I can no longer think properly, I considered. However, that there really was a parasite in my brain was not a delusion, but a proven fact. I figured that I could doubt my brain only after I had learned the truth about this parasite.

I looked into the author of a paper that was of particular interest to me. And I learned that this author worked at a university hospital not far from my parents' house. I couldn't help but feel a kind of destiny from that. And that was what led me to you, Dr. Kanroji.

Sent: 06/11/2011 Subject: Re: I'm sorry about the other day

This is Kanroji. I've read your email. That certainly explains why you suddenly started talking about a paper. Thank you for your detailed explanation. I have a much better idea of the situation now.

Now, let me be honest, I am very surprised. But to explain my surprise, I believe I'll have to tell a rather long story of my own.

I ask that you keep everything written below a secret.

It happened half a year ago. Two patients suspecting a parasitic infection came to visit me. We'll call the man Y, and the woman S.

Y and S were a married couple over twenty years apart. In addition, it was the husband Y who was the younger one, unusually. They were an extremely intimate couple, and while it had been half a year since they married, they had a charming air about them like lovers who just started dating.

The two reported having chronic headaches, and an MRI brain scan showed cysts in several places. Strongly suspecting a brain parasite infection, I extracted cerebrospinal fluid from both for a definite diagnosis, and discovered several parasites about a millimeter long.

Up to that point, things seemed fine.

When I looked at them under a microscope, I doubted my eyes. The appearance of the parasites taken from their cerebrospinal fluid didn't resemble any parasite I'd ever laid eyes on. They were shaped like teardrops, with two suckers around the pointed end. There was a pair that appeared to be mid-copulation, two bodies adhered together in a Y shape. Based on characteristics of form, it didn't seem likely they were trematodes, but I didn't know anything beyond that. After several days of research, I concluded that the parasites extracted from the couple were a new species.

Considering the brain could be the target of infection, I took caution in treating them. The worms, which infected the central nervous system, could not be excised recklessly. There were cases where cysts would fossilize and remove the need for treatment, and sometimes the inflammation reaction that resulted from treatment could be worse than the disease itself.

However, it was also not a situation where I could hesitate. According to Y and S, a while after the headaches began, they experienced strange changes in their mental state.

Both of them said they couldn't help but be bothered by the smell of others. This hadn't been the case before, and they claimed to have had fairly dull senses of smell, but as their headaches receded, they became disgusted by other people's body odor. It wasn't the smell of sweat or the smell of perfume; even smells so normal they wouldn't even be called smells felt so unpleasant, they felt agonized interacting with others.

The couple was certainly uneasy, and asked me if there was a connection between the parasites and these symptoms. Personally, I could only answer that I didn't know at the current time. An external head wound could damage the olfactory nervous system that linked the smell receptors and the brain, and a brain degenerative disease could damage the olfactory nerves themselves, causing the loss of smell. However, a case like theirs where the sense of smell became oversensitive was not often seen. It was a possibility that an infection in the paranasal sinuses or mouth caused smell abnormalities, making ordinary smells displeasing, but... considering the point that both of them displayed the same symptoms, it felt better to suspect that their hyperosmia was psychogenic in nature. At the same time, I hadn't forgotten that compulsive disorders could result from the onset and progression of organic brain diseases.

However... To tell the truth, I didn't pay much heed to their mental illness itself at first. Perhaps it was a kind of folie à deux - at any rate, I thought it best to prioritize removal of the parasites. I supposed that as long as the cause was cut off, the mental symptoms would also be eased.

Yet, when I was about to enact treatment, Y and S stopped showing up at the hospital. I tried calling them, but they refused to come to the hospital for seemingly on-the-spot reasons like being busy with work or not feeling well. And it didn't happen just once or twice. To my eyes, their behavior seemed protective of the parasites. What they were thinking, I had not the faintest idea. Surely if you heard there was a parasite in your brain, you would normally want to have it removed no matter what.

And then you appeared, Izumi. There were many similarities between your symptoms and theirs. A minor headache, an escape from interacting with others, a denial of treatment. I examined you thinking it couldn't be so, but I found your test results were nearly the same as Y and S's. It isn't as if I've confirmed the worm itself, but I don't doubt the parasites in your skull are the same as the ones in theirs. And I'm considering that, as aforementioned, those parasites may have caused your mental disorder.

Of course, I can't draw a definite conclusion at the moment. After all, this parasite has only infected a mere three people. No general approaches can lead us anywhere from there. We could even consider it all a coincidence. But I don't believe this is a simple trick of fate. My sixth sense is telling me I'm only looking at the tip of some massive secret.

Sent: 06/11/2011 Subject: Thank you very much!

It's Izumi. Thank you for your quick reply. I was thinking that nine out of ten people would ignore it as the ramblings of a madwoman, so I didn't expect such a detailed response! I'm very glad.

I also can't help feeling that there is some kind of connection between Y and S's mental symptoms and my own. Of course, I haven't even seen the two of them in person, so my hunch may be more wishful thinking than a sixth sense...

But if you say so, Dr. Kanroji, I think it must be true. I trust your judgement.

I'll visit the hospital on June 14th. I hope I can speak without being nervous this time.

Sent: 06/20/2011 Subject: About a fourth patient

This is Kanroji. There's been a new development regarding the new species of parasite, so I'm letting you know. As per usual, please keep the contents of this email secret.

The other day, I identified a fourth person who was infected. A woman named H, the youngest of them all thus far. Like previous patients, H came to the hospital citing chronic headaches, rejected treatment of her parasitic infection, and showed a strong trend of avoiding relations with other people. Examination of her brain also showed a cyst-based focus, and by further comparisons, I came to the decision that it was brought about by the same parasite. Also, in H's case, her drift away from other people materialized in the form of scopophobia. It does seem there are personal differences from patient ot patient in how the symptoms manifest. At any rate, there is little room to doubt that the worm is the cause of these mental illnesses.

What I can't understand is why four patients with a never-before recorded parasitic disease have come to me in rapid succession. To my knowledge, the same parasite has not been extracted from any patients at any other hospitals. Also, the four patients I've examined do not have any history of traveling abroad, and live in various regions, and I could find no common points to speak of. As a result, I'm currently unable to grab even a clue about how these patients came to be infected by the parasite. Perhaps this worm was just brought to this country from abroad by some means, and is in the process of expanding its range.

Relevant to this fourth patient, I'd like to answer a question you asked me during your examination on the 14th. To jump to the conclusion, it is as you feared. I am conducting experiments with the new parasite using my own body. I've done this not just for the treatment of the patients, but out of curiosity as a scientist. Thus, to be specific, H is actually the fifth case of infection.

It hasn't been many days since the infection, so there have been no symptoms that could be called symptoms yet, but the worm is gradually multiplying inside my body. If my expectations are correct, I will eventually exhibit a mental disorder like yours. Also, in the process of treating Y and S, I have found that no surgery is necessary to remove the parasites; application of albendazole and corticosteroids is effective, as with other brain parasitic diseases. As such, you may rest easy knowing there is no chance of it turning severe. It would be a waste for the doctor to collapse, after all.

Still, how is it you knew then that I was infected with the parasite? When you asked, it appeared to me that you were convinced I had the worm in my body. Was there some kind of external change you could observe? If possible, could you tell me the reason?

Sent: 06/21/2011 Subject: Re: About a fourth patient

It's Izumi. I'm relieved to know there's no worry of anything serious. Still, I see you really are passionate about research. I take off my hat to you. That said, please be kind to yourself, and don't push too far.

How could I tell the worm was in your body? To tell the truth, I don't know. The moment I saw you that day, it simply occurred to me. "Ah, the doctor's become the same as me."

Perhaps I did subconsciously notice minuscule changes in your expression and actions, and that conclusion was the only way I could explain that nagging sense of wrongness. But I really don't know the truth. I think it really was something that just wormed its way into my head.

Now, this will seem sudden, but I want to talk to you about something. Even I have to say it's something rather abnormal, so please take it with a grain of salt, and consider it the nonsense of a mad patient.

Lately, I've been thinking about you for the entire day. When I wake up in the morning, before I put on makeup, when I dry my hair, during work, not a moment goes by without it. What day we'll meet next, what clothes I should wear, what I should talk about, what I should do to let you know more about me... It's all I think about.

You may be somewhat aware of it too, but it seems I'm in love with you. I'm conscious of the fact that it's likely a kind of positive transference. And I'm deeply aware that revealing this fact to you will only cause you worry. But as much logic as I apply, it's not easy to feel satisfied by it.

It may be that this will lead me to cause you immense trouble in the future. So I will apologize in advance. I'm terribly sorry. And please, don't abandon me.

Sent: 06/24/2011 Subject: Progress report

This is Kanroji. I'll give a brief report about the change in my mental state caused after infection.

The first change was that seeing patients became agonizing. At first I considered it to be work fatigue, but before long, it extended from "patients" to "any other people." This symptom matches the "escape from interactions with others" that the four have in common. Though the manifestation varies - in Y and S's case, "being made uncomfortable by other people's smell," in your case "fearing causing harm to other people," and in H's case "bothered by other people watching"... I consider them all the same at their root.

This is my theory: In essence, those infected with the worm become misanthropic. I'm hypothesizing that the differences in exact symptoms between the four are a difference in what each of them traces this baseless misanthropy forced upon them by the worm back to.

Of course, I am unsure what merit there is to the worm depriving its hosts of socialization. ...To provide an example, certain kinds of tapeworm will cause small crustaceans known as Artemia, which normally act independently, to act in a group. Because by doing this, they can increase the odds of the Artemia being eaten by their final host, the greater flamingo. So I could understand bringing hosts together to such an end. However, what meaning could there be to the worm isolating its host?

That we are finding adult worms in our bodies means that humans are the worm's final hosts. The final host's role should be to spread eggs and larvae, so it's clearly not logical to isolate the human. Perhaps there is some deeper goal that we cannot imagine.

The second change, you can probably guess. I have some slight resistance to expelling the parasites from my body. But I will omit further explanation. Cases of the host becoming almost attached to parasites that should be harmful to it are not unusual enough to be worth mentioning.

The problem is in the third change. This relates to the "nonsense" you wrote about in your previous email.

Truth be told, I was very glad to read your confession. No, not exactly - and I know as a doctor, this is improper - I think I may have an even greater affection toward you than you toward me. Regardless of the definite progression of misanthropic symptoms, those thoughts only grow stronger by the day.

However, we must not jump to conclusions. Before any premature celebration, there is a matter we must first consider.

When putting the worm in my body, there was something I had decided in my heart. Namely: I would examine every psychological change that followed with suspicion. Once under the worm's influence, I can no longer be certain how much is my own will and how much is not. Which means I can only suspect everything.

As such, I question these feelings of romance. And I am not just doubting them at random. I have an idea.

In observing Y and S, I have witnessed a deeply intriguing change. Treatment has progressed, the effects of the worm weaken, and their misanthropy is certainly improving, but as if contrary to that, I notice their hearts growing apart. Two months after their treatment began, that sense of newlywed intimacy I felt when I first met them seems to have gone without a trace.

At first, I explained it as a result of the anxieties about this unidentified disease putting them in a state like "falling off a suspension bridge." That with the urgent danger gone, they had run out of material to fire up their love. But having now personally experienced infection by the worm, I can't help but feel some deeper meaning to the change in their relationship. As if, for instance... their love was something that was being maintained by the worm.

Izumi, what I want to tell you is more or less this: As long as there is the possibility that the worm influences even its host's romantic feelings, we should not easily draw conclusions about our feelings.

I hope you can make a calm judgement.

Sent: 06/25/2011 Subject: A few questions

In other words, you're trying to say that we're not in love, but that the worms in our bodies are in love?

I'm sure a layperson like myself couldn't understand... but let's say there is a worm that has the power to make hosts fall in love with each other. Why does it need to have such an ability? Even if that is one of the worm's strategies for propagation, why would it make infected hosts fall in love with each other?

It would be understandable if the infected were made to fall in love with someone healthy, increasing the chances of infection. But what reason could there possibly be for bringing together only those who have already been infected?

Doctor, are you trying to tell some plausible-sounding lie to keep me away and avoid hurting me? I can't help but suspect that's what it is.

Sent: 06/28/2011 Subject: Re: A few questions

Your doubts are understandable, Izumi. I have been plagued with the same doubts these past few days. How would making two hosts in which the worm has already established itself fall in love prove advantageous for propagation?

I had a flash of insight into a possible answer to that question just yesterday, while walking down the avenue. (I often take such aimless strolls when I'm thinking.) I wracked my brains and couldn't find a good explanation, so while looking at Yoshino trees on the roadside, I thought on it.

When I was a small child, one of my friends was an oddball who got poor grades in elementary school, yet had high-school-level knowledge of biology. One day, I was walking with that friend to school under cherry trees, and with a sudden thought, he asked me a question. "Have you ever seen Yoshino trees with fruit?"

I told him that thinking about it, I don't think I ever had, and he proudly told me about how it worked.

"That's because Yoshino trees have strong self-incompatibility - a genetic characteristic that prevents self-pollination. In human terms, it's like a system that prevents inbreeding. Yoshino trees are clones artificially multiplied using grafting and stuff, so however they pair up, any cross-fertilization is always going to be inbreeding. So while a half-breed can be born from cross-pollination with another type of cherry tree, there can't be a kid from two Yoshino trees. And since Yoshino trees aren't often grown with other cherry trees, that's why they have hardly any chances to bear fruit..."

At that point in my recollection, it came to me.

What if the worm worked the same way as Yoshino trees?

What if the worm also possessed a system that prevented breeding between those with the same or similar genetics by recognizing blood relation?

I pursued that thought further. What if that non-self discrimination system was "forbidding reproduction of those who matured in the same host"? In order to reproduce with one who matured in a different host, it would be necessary to come and go between hosts. (Insect-pollinated flowers can't ask pollinators to take just the pollen, after all.) And to fulfill that objective, would it not be perfectly reasonable to suggest a strategy of making hosts fall in love?

It was an outrageous idea, to say the least. Due to a lack of basis, I am making some leaps of logic. And it does sound like the idea of someone who's read too much science fiction. I tried to laugh off this unrealistic idea. Indeed, it's not only plants and fungi; some animals also possess such a system of self-sterility. Ciona intestinalis, for instance. But even for the sake of genetic diversity, there could not possibly be a creature with such a complex, roundabout method of reproduction...

That's when I stopped in my tracks. I realized that there did in fact exist a creature that, regardless of being capable of parthenogenesis, took a "complex, roundabout method of reproduction." ...Yes, it goes without saying. I refer to the parasite you brought up in an earlier conversation: Diplozoon nipponicum.

It isn't restricted to D. nipponicum. For example, some kinds of liver fluke are hermaphroditic and capable of parthenogenesis, yet cannot mature into adults without two coming into contact. When you really think about it, this seemingly illogical and complex reproductive strategy is actually very commonplace in the world of parasites.

I am trying to investigate this idea further. If there truly exists a parasite that makes pairs of infected hosts fall in love, how might the infected recognize other infected? Surely, they must be sending some form of signal. I don't know what nature it has or its intensity, but... at any rate, I theorize the existence this signal is the reason for the implausible outcome of all these infected patients flocking to me one after another. Perhaps those infected by the worm are unconsciously brought together.

With this theory, the illogical-seeming strategy of making the host misanthropic also gains a possible explanation. For instance... what the intent of the worm's control is not isolation of the host, but bringing fellow hosts together? If all the members of a given group are infected by the worm, that group's exclusiveness and cohesiveness can be expected to skyrocket. In such an infected group made to have mutual cooperation, the capacity for continuation is higher than a non-infected group, and thus the chance of each member surviving would also be high. That would be an extremely desirable thing for a worm which makes humans its final residence.

Parasites having an effect on the host's sociability is something that has been pointed out long before. Even Dawkins pointed out that the highly-advanced social structures of termites were brought about by the control of microorganisms in their bodies. By mouth-to-mouth feeding, termites spread the microorganisms to the entire group, and it's thought that this action is induced by the microorganisms for reproduction. For a more extreme example, there even exists a theory stating that the social nature of vervet monkeys and Japanese monkeys, and consequently humans, was caused by a retrovirus. If viruses and bacteria can do so, then perhaps there's nothing strange about the worm being able to influence human society.

I have no such feelings of wanting to keep you away, Izumi. In fact, it's because I want to love you with such conviction that I am desperate to expel any shred of doubt.

Thinking about it, in these near fifty years of life, I have always been alone. Whoever I was faced with, my feelings were never shaken, and the more I got involved with people, the more hollow it felt. So soon after turning forty, I entered a kind of unfeeling state, passing the days and living though I felt like I was dying. But meeting you has brought back a trembling in my heart I haven't felt in a long time. When I talk to you in person, my heart aches like a young boy just learning love. And that is why I have misgivings. If these feelings were merely brought about by that worm, nothing could make a bigger mockery of humanity.

Sent: 06/30/2011 Subject: (no subject)

I'm happy you said that, doctor.

I'm very, very happy.

Enough that I would be fine just dying.

But if your theory is correct, then if the worm were gone, I would lose these feelings too.

I've come to think of that as a very sad thing.

I'll come to the hospital at the start of July.

So long.


The correspondence between the two ended there. Kousaka was silent for a while, still staring down at the documents.

He looked over the dates on the article and the emails again. Their email correspondence ended on June 30th, and by July 20th, the two committed suicide. Only God knew now what happened to them in that twenty-day period. They hadn't told anyone the most important part, taking that secret to their graves.

There was no question of Urizane's intent in showing him these. Kanroji and Izumi fell in love due to the worm's influence, and afterward, carried out a mysterious double suicide - so then it was highly likely that Kousaka and Sanagi who also fell in love due to the worm's influence would repeat the same thing.

That must have been it, more or less.

Kousaka returned the newspaper clipping and documents to Urizane. And he asked.

"Is the "H" mentioned here referring to Sanagi?"
"Yes, you're correct," Urizane affirmed.

Kousaka pondered for a few seconds, then asked another question. "Was Sanagi's personality different before she was infected with the worm?"

"That's a tough question." Urizane's mouth made a slight frown, and he scratched the back of his neck. "In a way, you're right, but... Things are a bit too tangled to say for sure."

"Which is to say....?"

Urizane shifted his body slightly to look out the window. The chair squeaked as he moved. The upper part of the view from the window was obscured by a long icicle hanging from the roof.

"I'll explain things in order, that included. The things that have happened to Hijiri in the past year. And the way in which the worm has ruined her life."

Urizane put his hands on his knees and sat straight.

Urizane began: It started with the suicides of a certain couple.

They were on good terms, they had no economic trouble, the husband's job went well, the wife was pleased with being a housewife, and their only daughter was growing up well. It was the very picture of a happy family. There was not a single reason for them to take their lives.

Yet there was no room for doubt in the fact that their deaths were suicides. The two of them holding hands as they lept off a bridge in the mountains had been witnessed by people walking by. ...That was about a year ago.

Only their daughter remained. Hijiri. She had only just turned sixteen, and had no other relatives, so she was put in the care of her grandfather on her mother's side - that is, myself.

For some time after I took custody of her, she hardly talked to me. It appeared not that she was refusing to talk, but that she had forgotten how to speak with others. She used to be a cheerful girl with many friends, but like a changed person, she became quiet, using as few words as possible even at a school. I thought then that it was from the great shock of her parents' deaths. Her late mother - though I hadn't heard for her in a long time - was my daughter after all, and I had been bereaved of my wife just two years prior, so I perfectly understood Hijiri's sadness.

However, the truth differed from my expectations. She was not merely saddled with grief.

She was thinking to herself the whole time.

Eventually, Hijiri said something with no prior warning.

"I don't think it was a suicide with mom and dad."

"What do you mean?," I asked. And Hijiri began to speak like letting a dam burst. About how her parents began acting strange about half a year prior to the suicides. They came to abnormally fear other people, and demonstrated illogical persecution complexes - "the neighbors are watching me," and "I'm always being followed."

"I found it strange how they suddenly got like that, but now, I finally feel like I understand the reason," she told me. "The two of them were sick. And it seems I've caught the same sickness."

I couldn't understand even half of what Hijiri was saying. However, when she not long after started to frequently skip school, and became distant with me, I finally understood what she meant by "sick."

She's walking down the same path as her parents, I felt innately. I could see that if left alone, she could reach a point there was no returning from. It did not seem like something that could be left to natural healing.

I took Hijiri to various psychotherapists and psychiatrists. But there were no important findings; all that became clear was that she had a fear of being watched by others, and there were no signs of improvement.

A breakthrough came from the words of a certain clinical psychologist. While explaining to me how the treatment was going, the young woman said, "That reminds me..."

"In the middle of an ordinary conversation, Hijiri said this to me. "There's a worm in my head." She didn't seem to expect much reaction from me, but it struck me. I thought it might be a lead to understanding her mind, so I asked her to explain in more detail. But she said it was a joke and dodged the question, and hasn't brought up the topic of a worm since."

Afterward, the clinical psychologist explained the common psychological interpretation of "a worm in my head." In rare instances, immense stress or dissociative disorders could cause such delusions of parasites.

However, I felt myself strangely hung up on the words "a worm in my head." Even when I slept, even when I woke, the words wouldn't leave my mind. I couldn't help but suspect a special meaning in her casual remark. I suppose it came from not perceiving things as a doctor, but an instinctive sense as her grandfather by blood.

Lately, it did seem she was having chronic headaches, and was consistently using painkillers. I had considered it a common thing for a girl her age, but once I began to suspect, I couldn't rest without confirming the cause.

I resolutely asked her myself, but Hijiri would not back down on the point of "I didn't say anything like that." So I fabricated a reason to draw blood from her, and went to have it tested.

I gulped when I got back her results. There was an increase in eosinophils and high IgE levels, characteristics found in allergic reactions and parasitic infections. Of course, I couldn't conclude from that alone that there truly was a "worm in her head," but it was clear at any rate that some change was occurring in her body.

I had a friend assist me in meeting a medical professor who specialized in the field of parasitology. That professor was Yutaka Kanroji - the man who became the center of this incident.

He was around his late forties, and had a moody scientific look, but was also quite tall with striking facial features. He was a charming man. He seemed famous in the area, known to be so passionate about parasitology that he wouldn't hesitate to infect himself with a parasite for the sake of research.

I spoke to Professor Kanroji. About the illogical death of the couple, the abnormalities in my granddaughter, her chronic headaches, the "worm in her head," and the blood results. I was prepared to be laughed off, but Professor Kanroji showed unparalleled interest. Above all, he seemed to have a sharp reaction to mention of the "worm in her head" and scopophobia.

Hijiri was made to take several special tests. The next week, I tried to take Hijiri with me to hear the results, but she denied, using her headaches as an excuse. I could see it was only temporary, but not wanting to force her to come if she didn't want to, I went to Professor Kanroji's hospital alone.

There, I was informed of the shocking truth.

"First, take a look at this."

Professor Kanroji showed me an MRI of Hijiri's brain. There, I could see multiple ring-shaped areas of contrast. Next, he showed me the blood results. Before I could look over the numbers, Professor Kanroji readily informed me.

"To jump to the conclusion, there is a parasite in your granddaughter's head."

I gasped, and slowly nodded. Some way or another, I was able to accept the truth with such calmness, even I found it odd.

Professor Kanroji continued. "However, in a sense, we could call your granddaughter extremely lucky. Of course, there's no question that the parasitic infection itself is unlucky... but it is nothing short of a miracle that you first came to me to have her examined."

Then he explained to me how he had other patients with similar symptoms to Hijiri. How they had a new species of parasite in their heads, how it was possible the "worms" might be manipulating their hosts' minds, but how it was perfectly curable with existing treatments.

The next day, I visited his hospital again with Hijiri. And Hijiri began treatment under Professor Kanroji. Such was how we came to be involved with the professor - but not a month later, we heard about his passing.

Professor Kanroji's suicide was all over the news. A medical professor committing suicide at a university institution was a story in itself, but the fact it was not just a suicide, but a double suicide with one of his patients, caused a major clamor. All manner of theories went around.

I showed Hijiri the newspaper article about Professor Kanroji's death. I knew there was no point in hiding it. She looked over the article, and said to herself, "Huh, like my mom and dad." That was the very same impression I had gotten.

"That doctor probably used his own body as a test subject for the parasite," Hijiri said with an unchanged expression. "And he was such a good person..."

"You see that parasite as the cause of his suicide too?", I asked, and she nodded as if it were obvious.

"The patient he committed suicide with was probably one of the infected patients. The woman who came to Professor Kanroji just before me."

I thought about it, then asked Hijiri this.

"I'll ask you honestly. Do you feel even the slightest desire to die right now?"

"I guess I'd be lying to say there wasn't any," Hijiri shrugged. "But that's been there for a long time. It didn't just start now. Enough to explain it as a gloomy personality."

I was relieved to hear that.

"Suppose this parasite is a dangerous creature that can cause the infected to commit suicide," she said, poking her forehead. "Maybe those symptoms can differ between people? If they didn't, the couple who first came to the hospital should have killed themselves a while ago."

"Aren't you scared?" I couldn't help but ask, perhaps from seeing my granddaughter accept the situation so calmly.

"I'm scared. But at least one more thing is clear now. Mom and dad didn't kill themselves and abandon me. The parasite just killed them."

With that, Hijiri smiled. Ironically, that was the first smile she'd shown me since coming into my custody.

I only noticed that evening that Professor Kanroji had sent me an email just before his suicide.

Maybe Professor Kanroji was worried up to the very end that he'd take his life and abandon his three patients. That's why he entrusted it to me, who worked in the same business, and as the relative of a patient, knew much about the circumstances around the worm. He probably sent me their emails as-is due to not having time to leave a concrete message.

I read over the emails between the two again and again, but still knew nothing about the mechanism that caused the worm to induce the death of its host. What was clear was that even an intellectual like Professor Kanroji couldn't resist the worm.

I carried on the treatment of Yuuji Hasegawa and Satoko Hasegawa - the "Y" and "S" mentioned in the emails. Parasitic disorders were not my specialty, but following the treatment in the emails, I continued the deworming of the Hasegawas and Hijiri.

Considering the four who had died so far were all couples of infected, I advised the Hasegawas to spend time apart for now. They readily took my advice. They even seemed relieved to have a justification for living apart. So it was just as Professor Kanroji said in his email. It seemed their relationship had been ruined beyond repair.

While the Hasegawas were recovering, Hijiri's symptoms meanwhile showed absolutely no sign of improvement. She should have been taking the same anthelmintics, but there was a striking difference in their effectiveness. The Hasegawas' misanthropy gradually lessened, but Hijiri's would not improve, only worsen.

That made sense, as it turned out. Because Hijiri wasn't taking the anthelmintics.

One day, I happened to witness it. I was present when Hijiri threw the medicine into the trash without taking it. Hijiri met eyes with me, and didn't apologize; she just shrugged, as if to say "you can get mad if you want to."

That one time, I reprimanded Hijiri. I asked her if she knew what she was doing, and she sighed with a fed-up look. And she muttered this.

"I don't need to be cured. I don't care if it kills me. I want to say goodbye to this world quickly."

That's because of the worm in your body, that's what it's making you think to protect itself - as much as I tried to tell her, it had no effect. Soon, she dyed her hair bright, and got her ears pierced. She skipped school, and read nothing but old philosophy books and writings about parasites.

It seemed that to expel the worm in Hijiri's body, it would be necessary to cultivate a desire to be cured. However, I had no idea how to give her a positive attitude about deworming.

That was when Mr. Izumi appeared. The surname of this man who came to me out of the blue without any appointment sounded familiar. And of course it would. He was the father of Ms. Izumi, the woman who committed suicide with Professor Kanroji. He had also received an email from Professor Kanroji, and was aware of the existence of the worm.

He was a bodyguard, currently working for a major defense corporation, but my first impression of him was that rather than a bodyguard, he was more of a scientist or engineer. His way of speaking had that kind of logic. Mr. Izumi did not despise the insolent doctor who had carried out a double suicide with his patient. In fact, he respected Professor Kanroji as a brave doctor who was trying to cure his daughter, at the ultimate cost of his own life.

I found it strange that he could be so calm. If it were not his daughter but my granddaughter who had killed herself with Professor Kanroji, could I respond so gracefully? No, I believe that would be impossible.

Mr. Izumi came to me asking whether there was anything he could do to help exterminate the worm. At first, I politely declined. I appreciated the offer, but honestly was doubtful a layman like him could provide any help.

He clung on, however. Please, let me help somehow, he begged. I saw an unusual light in his eyes. I made a guess: Perhaps this Mr. Izumi wants his daughter's death to have some meaning. For his daughter's death to serve as an impetus to move him, and that leading to the salvation of other patients - was that the kind of development he sought? Perhaps I was just barely capable of giving him something of the sort.

I deeply sympathized with him, and gave his request further examination. And I came upon a job that he could be tasked with.

When I told him that Hijiri was pessimistic about treatment and had a weak will to live, he jumped on it.

"Leave that to me." He thumped his chest. "I'll definitely get your granddaughter to open her heart."

And so Mr. Izumi began his efforts to bring back Hijiri's will to live. And before long, he found you. It was a complete coincidence. Mr. Izumi was merely looking for people who might form a close relationship with Hijiri, and did not imagine he would happen to find another person infected by the worm.

In any event, this resulted in you and Hijiri falling for each other, and her opening her shut-off heart. If I hadn't heard out Mr. Izumi's request out of sympathy, Hijiri would likely still be alone and holding the darkness in her heart to herself. I suppose this is why they say: the good you do for others is good you do yourself.


The story ended there. Urizane held his throat and cleared it. He must have been tired from talking.

Kousaka tried to mentally sort out the contents of the emails he read and Urizane's story. The three broad points that were clear about the "worm" in his body - and in Sanagi's - were as follows.

1. The worm isolates its host.

2. The worm makes hosts fall for each other.

3. When certain conditions come together, the worm's hosts kill themselves.

"In short," Kousaka spoke, "you've called me here to kill the worms before Sanagi and I meet the same fate as Professor Kanroji and Ms. Izumi?"

"That's correct."

"Which means..." Kousaka thought. "You're going to pull Sanagi and I apart?"

"Precisely. It was none other than ourselves who brought you together, but the situation has changed. The reason Mr. Izumi hired you to be Hijiri's friend was in hopes of opening her heart and regaining her will to live. His judgement was not wrong, but... if that was the worm's doing, then that's a different story. I'm very sorry, but I can't let you be with Hijiri any longer. In case the unthinkable happens."

Kousaka tried imagining the "unthinkable" Urizane spoke of. The instant picture of him and Sanagi committing suicide together resounded surprisingly well in his heart. I see - as we are now, it wouldn't be too strange for things to end up that way, Kousaka thought, as if he weren't even part of the equation. If Sanagi asked him to do it, Kousaka probably wouldn't refuse, and if Kousaka asked her to do it, Sanagi probably wouldn't refuse either. "It's hard to live" sufficed as a reason.

Maybe it was only a matter of time before Kousaka arrived at that idea, and it just hadn't happened yet. Perhaps as soon as tomorrow, he could have arrived at the idea of a double suicide on his own, and suggested it to Sanagi. Thinking it gave him a chill.

As Kousaka pondered silently with folded arms, Urizane spoke.

"I won't ask you to reply right away. I assume you need time to sort out this sudden influx of information?"

Kousaka nodded.

"I'll send for you in five days. Please decide whether you'll undergo treatment or not before then. The treatment itself is simple, so no real preparations are necessary, and we can begin as soon as you have an answer."

Kousaka recalled how Kanroji's emails had mentioned that the treatment didn't require any surgery, and just medicine was enough.

"Of course, I'm personally hoping that you shake off the temptation of the worm and go through with treatment. However, I won't force you. Unless they were a relative, I wouldn't force treatment on a patient with no desire to be cured."

Five days, Kousaka repeated in his mind. He had to come to a decision by then.

"And I'll add just in case," said Urizane, "if you deny treatment, you will never meet Hijiri again. I don't know if she'll accept treatment or not, but in either case, it would be too dangerous to let once-infected persons stay together."

"Right," Kousaka said. "And my germaphobia and misanthropy won't be cured either."

"Indeed. And even if you do undergo treatment, until we can be sure the worm is fully gone from both your bodies, I can't let you come near Hijiri. I take it you understand?"


Then Urizane seemed to remember something, opened a desk drawer, and handed Kousaka a photograph. It showed something resembling an inkblot used for a Rorschach test. From the progression of everything prior, Kousaka had some idea of what this unclear image was.

"Is this a photo of the worm?"

Urizane nodded. "Seeing that photo must make it feel a little more real, yes? Pictured there is two of the worms fused together. It was mentioned in Professor Kanroji's emails, but it seems when this parasite meets another in a person's body, their male and female sexual parts link up, and they adhere together in a Y shape."

Kousaka looked at the photo again. The worms, dyed a faint red, seemed to him to look less like a Y shape, and more like a heart drawn by a young child.

When Kousaka returned to the waiting room, Izumi and Sanagi sitting on the back sofa looked up. Kousaka smiled at Sanagi, but she averted her eyes and lowered her head.

"Seems you're finished," Izumi said. "I'll send you home."

"See you, Hijiri," Izumi said to Sanagi. It seemed she was staying here. Perhaps this was a hospital as well as a household, so she lived in this clinic.

Kousaka stopped in front of Sanagi, wanting to say something to give her relief before he left. But he didn't know how to speak to her.

No, he did know, really. Just say "Even after hearing all that, my feelings for you won't change, so don't worry." It was simple.

But Kousaka couldn't do that. He didn't have the confidence in his own feelings he did before.

Thinking back, it was all unnatural from the start, Kousaka thought. Why was Sanagi captivated by a good-for-nothing like me? Why did our compulsive disorders improve when we were together? Why did love bud between us with such a gap between our ages? There were just too many illogical aspects.

But if it was all an optical illusion caused by the worm, it lined up. Sanagi and I didn't fall in love. The worm inside me and the worm inside Sanagi fell in love.

He felt like he'd been expertly swindled. Like a swingback from the happiness he'd felt just a few hours ago, Kousaka's feelings rapidly sobered.

In the end, he left the clinic without a word to Sanagi. On the drive back, Kousaka just gazed out the window absentmindedly, but as they neared the apartment, he said to Izumi, "Um..."

"There was one thing I neglected to ask about the worm..."

"What?", Izumi asked, still looking ahead. "I'll answer if I can."

"Has its route of infection been identified?"

Izumi shook his head. "It's unclear. But Urizane's thinking it's probably oral infection. You were probably unlucky enough to eat food with the worm in it. You got any ideas?"

"Unfortunately, no."

"Thought so. ...Any other questions?"

"Does the worm spread from person to person?"

"It does." He replied quickly. Izumi seemed prepared for that question. "The adult worm resides in the central nervous system, but eggs and larvae move around the body through the bloodstream. ...But just living together won't spread it. Or else the worm wouldn't go to the trouble of making hosts fall in love. You get what I'm saying, right?"

"Yeah," Kousaka said. "It's sort of like a sexually-transmitted disease, isn't it?"

Izumi grinned. "If you don't wanna be shy about it, yeah. So, we know your worm didn't spread from Hijiri Sanagi. It's been lurking in your body since long before."

"I know. I wasn't doubting Sanagi. I was just curious."

Izumi's answer finally solved the mystery. On December 20th, Sanagi tried to kiss Kousaka while he was sleeping. But she caught herself just in time, and said: "I was just about to do something there was no coming back from."

Sanagi was probably plotting to spread the worm to Kousaka then. At the time, no one was aware that Kousaka was a host of the worm. And Sanagi knew that hosts of the worm would be brought together by a forced love.

Sanagi was planning to make their relationship perfect by spreading the worm to Kousaka. But just before she carried it out, she came to her senses. She awakened to the fact that she would be putting Kousaka's life in danger, couldn't bear to face him after that, and ran away.

That seemed to be the reality.

After dropping Kousaka off in front of the apartment, Izumi spoke.

"I'll come in the afternoon five days later. Get yourself ready by then."

"I don't think it'll take that long."

"Don't have to overthink it. It can happen to anybody. Alcohol, loneliness, and darkness can trick your eyes, and make you see a destined love. And when the two wake up sober the next morning, they notice the mistake they made. That's the same thing that's happened to you."

With no more to say, Izumi left.

Kousaka didn't go straight inside; he stood by the entrance and gazed at the light pouring out the windows of the apartment and nearby residences. Thinking how through those windows were people living totally different lives felt strange. It had been a long time since he was conscious of others' lives in that way.

Then out of nowhere, Kousaka thought about his mother's death.

I wonder. Perhaps I wasn't the only one infected with the worm then.

Perhaps my mother's suicide was caused by the worm.

In the month before her suicide, she was uncharacteristically kind, and treated him affectionately. That had never made sense to him all this time. The mother he knew wouldn't admit her own faults even if the world went topsy-turvy.

But if that were because of the worm, then he could accept it. His mother, made misanthropic by the worm, could only open her heart to Kousaka, similarly infected with the worm. The worm in his mother's body and the worm in his body were calling to each other.

Strangely, he felt cheerful. Now I can hate my mother without reservations, Kousaka thought. To her very last, she couldn't love Kousaka of her own volition. That fact cleared up a discontentment in his mind.


Chapter 7: Bed Bugs' Bite

Kousaka spent the first two days as usual. "As usual" meaning the usual before he met Sanagi. He lay in bed and read books, and when he tired of that, he messed around on the computer, eating a bare-bones meal when he felt hungry. Rather than thinking and thinking, his priority was to regain a mental state where he could calmly think. He supposed clearing his head and taking things slow was the best way to do that.

Reasonably speaking, there was no way he could refuse the treatment. He certainly didn't want the yet-incomprehensible worm manipulating him and making him kill himself. And most importantly, exterminating the worm could cure the germaphobia that had plagued him for many years.

However, there was resistance. It was a primal fear that everyone experiences before a major change. His life thus far had been centered around his germaphobia and loneliness. For better or worse, he had gotten used to that kind of life. Taking away those two pillars would mean having to rebuild his life from scratch. That might be fine for a teenager, but in his late twenties, was rebuilding from scratch realistically possible?

Other than that concern, he was generally in favor of treating the worm. Logically, he was 90 percent of the way there, and emotionally, he was 60 percent.

On the third day, he was contacted by Izumi. His email said "There's someone I want you to meet." Kousaka went out to the specified coffee shop, and met with a young man. The man's face still looked childish in places, and it didn't seem he could have been long out of college. But he was the first patient infected by the worm mentioned occasionally in Kanroji's emails, Yuuji Hasegawa, AKA "Y."

Kousaka heard from him how the Hasegawas met each other. How the couple over twenty years apart met, how they were drawn to each other, how they were wedded. And how that passion faded.

The way they met sounded exactly like how Kousaka and Sanagi met. The more Kousaka listened, the more shocked he was by the sheer number of commonalities. An unexpected meeting between two people with opposing personalities, gradually being drawn to each other after learning of each other's mental illness. The two misanthropic people learned of the one person in the world they could make an exception for and trust. The two overcame the difference in age and were wedded...

"But it was nothing more than lovesickness," Yuuji Hasegawa said, looking into the distance. "Once I started taking the deworming medicine Urizane provided, my feelings for my wife cooled in a blink. I can't remember what captivated me about her and convinced me to marry her. It seems she's the same way. Divorce is only a matter of time."

Kousaka saw his own future there. With the worm gone, their relationship would cool, and maybe it was most suitable for things to return to their normal state. Because those feelings were only temporarily heated by the worm.

Our love is probably also just a "lovesickness," Kousaka thought. Then he recalled the day he first met Sanagi. Specifically, the street performer he saw outside the train station. He put on a show with his two marionettes. A farcical play. Were the puppets aware they weren't really in love, it was just the puppeteer making them fall in love? I can't know that. But at any rate, our love is no different from those marionettes' love. It's just the minor difference of whether or not you can see the strings.

By the time Yuuji Hasegawa was done talking, Kousaka's mind was made up. I'll take the treatment, he vowed. Even if it ends my love with Sanagi, I won't care. Continuing this relationship with her, knowing the truth that the worm is using me, surely I wouldn't be able to treat her with feelings as pure as before. In a sense, their relationship was over the moment he heard Urizane's story.

Kousaka thanked Yuuji Hasegawa and left. When he got back home and hung up his coat, he noticed the scarf from Sanagi there.

For a moment, the thought of disposing of it crossed his mind. Maybe I'll never be able to let go of my attachment to Sanagi if I keep this thing around.

However, he quickly reconsidered. I shouldn't take any extreme actions. Like with quitting smoking or drinking, forcing yourself to hate something often resulted in its charm becoming stronger. I should slowly forget Sanagi over time. No need to rush.

Kousaka put away the scarf in the closet. He went into the bathroom and took an hour-long shower, changed into clean clothes, and got in bed. When he closed his eyes, the events of the past month arose and vanished behind his eyelids. Each and every one was an irreplaceable memory. Don't be swayed, this is all the worm's doing, Kousaka told himself. It's like the withdrawals of a drug addict. If I just endure them, they'll go away soon.


And then the fourth day came.

Tomorrow afternoon, Izumi would come pick him up, and he'd start treatment. Once he did, he'd probably never meet Sanagi again. It seemed they would be allowed to meet again once they were both fully rid of the worm, but by then, they'd have lost interest in each other. They'd be going on with their own lives.

I should meet Sanagi one last time, Kousaka thought. If we just part ways like this, her existence will probably always cast a shadow on my memories. We need to separate with the proper process. I think what "goodbye" means when parting ways is "Please forget me. I'll forget you."

I have to say goodbye to her.

Kousaka took the smartphone on his desk. While puzzling over whether to call her or send an email, the phone vibrated in his hand.

It was an email notification from Sanagi. It seemed she was thinking the same thing at the same time.

It was a simple message. "Can I come over there?"

Kousaka typed three letters, "Yes," and sent it.

A few seconds later, the intercom sounded. Thinking it couldn't be so, Kousaka opened the door, and found Sanagi standing there. She must have already been there the moment she sent the email.

She wore a cotton pea coat over her school uniform. She wasn't wearing her usual unrefined headphones. When dressed so averagely, Sanagi looked like a normal girl with nothing wrong with her. When she met eyes with Kousaka, she reflexively looked away, but slowly brought her gaze back to him and lightly bowed her head. It was modesty unlike Sanagi.

Though it had only been three days, it felt like a long time since they'd seen each other. The moment he saw Sanagi, his resolution quickly wavered. As much as he broke it down, it was hard to resist the charm when faced with the real thing.

He had a strong urge to hug her right away. But he desperately resisted it.

To calm himself, Kousaka imagined the scene of the worm in his head firing out things related to romantic feelings like nerve signals and hormones and such with incredible force. Of course, the reality was surely a little more complex than that, but the important part wasn't having an exact picture, but being conscious of how it was controlling him.

Sanagi didn't head for the bed today. She didn't take off her coat or shoes, and just stood at the front door, not even entering the room. Maybe she thought she didn't have the right to cross the threshold of this room anymore.

Kousaka broke the ice. "You want to talk?"

"Mr. Kousaka, are you going to kill the worm?", Sanagi asked hoarsely.

"I think that's probably what I'll do."

She didn't seem to celebrate nor grieve that response, and just emotionlessly said "I see."

"You will too, right, Sanagi?"

Sanagi didn't answer that question.

Instead, she replied like this.

"There's one last thing I want to show you, Mr. Kousaka."

Then she turned her back to him and left the entryway. Telling him to come along, surely. He hurriedly grabbed his coat and wallet and went after her.

They took several trains in heading to their destination. Kousaka asked where they were going, and Sanagi wouldn't answer, saying it was "secret." After switching from the JR to a private railway, the scenery outside the windows gradually simplified. The train sped along tracks that ran between mountains covered in white snow. The distance between stations increased, and the passengers aboard decreased.

Kousaka looked out the window and thought. Sanagi said "there's one last thing I want to show you." The identity of "what I want to show you" was of course on his mind, but even moreso was the meaning of "last." Was it a temporary "last" since they wouldn't meet for a while once treatment began, or a permanent "last" that indicated Sanagi had no intention of taking the treatment, and they'd never meet again...?

He heard the announcement of the next stop. The train came to a halt in no time, and Sanagi looked up from beside him. The two got off the train and left the deserted station.

Mountains and plains extended as far as the eye could see. There was nothing else to really look at. Kousaka could identify three houses, but they all looked very worse for wear, and it was dubious if people lived in them. Everything in sight was covered in snow, and even the center of the train tracks was unclear. Thick clouds hung over the sky, snow blowing off the ground obscured vision like a fog; a darkness distinct from night filled the area. It looks just like a monochrome photo, Kousaka thought. What did Sanagi intend to show me in this place at land's end?

Fierce winds instantly chilled their bodies which had been warmed in the heated train. Their faces and ears directly exposed to the air stung. No doubt, it was below freezing. Kousaka buttoned his coat up to the neck. When he took out his smartphone to check the time, the signal strength indicator showed him as out of range. That was how remote this place was.

Sanagi began walking toward one of the houses with no hesitation in her step. The snow impairing their sense of distance, it was hard to tell at first, but there was a considerable distance to the house. On the way, Sanagi kept turning around repeatedly to confirm that Kousaka was following. But he wouldn't walk alongside her. If Kousaka started falling behind, he would walk quicker, keeping about a 3-meter distance.

After about ten minutes walking, they finally arrived at the house. It couldn't be more perfectly deserted. A two-story wooden building, with faded election posters and metal signs put up without consistency on the outside wall. The windows were shattered to bits, and the roof bended under the weight of the snow, ready to collapse any moment.

Sanagi took Kousaka around to the back of the house. There was a light blue container there. A cargo container about 3.5 meters long, 2.5 meters wide, and 2 meters tall. Maybe the house's owner used it for storage. There was red rest on it in places, but unlike the house, it could still serve its function of storage.

Sanagi headed straight for the container. It appeared that what she had to show Kousaka was inside it.

Even after reaching this point, Kousaka couldn't even imagine what it might be. He hadn't found anything resembling a lead. What could be here, in this remote place, in a storage container behind an abandoned house? Surely she didn't want to show him a tractor or a dynamo.

Sanagi entered the container without a word. Kousaka followed. The interior was fully boarded, but even so, it smelled of rusty metal. Kousaka expected to see trash scattered around, but the container was mostly empty. Just steel shelves attached to both walls, with nothing on top of them.

Kousaka was confused. Was this empty container the thing Sanagi wanted to show him?

He turned around to question her at almost the same time the door closed. In an instant, everything went dark. Just afterward, there was an ominous clicking sound. He ran over and pushed the door, but it was firmly shut.

It seemed it had been locked from the outside.

At first, Kousaka thought Sanagi had gone outside and locked the door. But then he noticed a quiet laugh beside him. She had been locked in the container with him. Which meant there was someone else outside who locked it. Though he hadn't sensed them at all.

"Well." Sanagi cleared her throat. "Now we can't leave."

"...Is this your doing, Sanagi?", Kousaka asked, facing the darkness where he thought Sanagi was. "Were you lying about having something to show me?"

"Sorry. But don't worry. It's not like I'm going to force you into a double suicide here, Mr. Kousaka," Sanagi said, as if sneering at his bewilderment. "I just want to negotiate. If you accept my conditions, I'll let you out of here right away."


"It's really simple."

Gradually, Kousaka's eyes got used to the dark. A faint light from a vent around the ceiling dimly lit the container.

Sanagi stated her conditions.

"Don't kill the worm. Promise you'll refuse the treatment."

It was a development that was easy to predict with some thought. Even if her attempt had ended in failure, she had a prior record of attempting to spread the worm to Kousaka. So Sanagi was a girl who didn't entirely hate the worm, and had ideas of using it proactively.

"Hey, Sanagi," Kousaka began cautiously. "Why are you so attached to the worm? Urizane must have told you. If we leave the worm alone, we might lose our lives."

Sanagi shook her head. "That's hardly certain. It could just be coincidences. After all, Yuuji Hasegawa, the first to be infected, is doing just fine, right?"

"But at the very least, it's clear the worm makes hosts misanthropic. At this rate, we'll never fit into the world. Are you just fine with that, Sanagi?"

"I am," Sanagi replied without hesitation. "I was misanthropic before the worm infected me. I had a lot of friends, but deep inside, I was sick to death to them. I couldn't like any one of them. So I couldn't help being anxious about what everyone thought of me. Sooner or later, this would be my fate anyway. Just getting rid of the worm won't solve the fundamental problem."

"You might be right. But even resolving surface problems should make it much easier to live."

"It won't."

Kousaka sighed. "Is the worm that important?"

"It is important. Because I really loved the time I spent with you, Mr. Kousaka."

Sanagi's honest words shook Kousaka's heart violently.

He rebutted, half to convince himself.

"I feel the same. My time with you was irreplaceable and wonderful. But even that's just an illusion caused by the worm. We didn't fall in love of our own will, it's just the worms inside us who did."

"So? So what if it's an illusion?" Sanagi's voice went shrill. "What's wrong with a sham of a love? If I can be happy, I don't care about being a puppet. The worm did things for me that I couldn't do. It taught me how to like people. Why should I kill such a benefactor? I know about the puppet strings, and I'm leaving myself to them. If that isn't my own will, then what is?"

Kousaka had no idea how to respond. Because Sanagi's argument was a clear statement of something hazy in the corner of his mind. When a puppet approves of the fact they're a puppet, can that be called an act of free will? No one can say.

There's a neuroscience experiment that goes like this. Experimenters instruct subjects to "move the fingers of whichever hand you like." When this happens, the motor cortex in either the left or right brain is given a magnetic stimulation. And the subject moves the fingers of the hand opposite the brain hemisphere which received the stimulation. Yet they have no awareness of the magnetic stimulation controlling them, and are convinced they decided which hand to use of their own will.

This experiment shows just how reliable human free will can be. Depending on your perspective, you could even say it partially proves the correctness of determinism. But some scientists will point out: What if the stimulus wasn't causing intent itself, but simple preference and desire, and the subject merely considers these to make their decision? Maybe the magnetic stimulation simply narrows the options, and the final choice is left to the person themselves.

The same could be said of Sanagi's choice. You could say it was a decision influenced by the worm, but you could also say it was a self-made decision "with the worm's influence." That's effectively what she was saying.

It was a stalemate. As much as they argued, they likely wouldn't come to a conclusion. She wouldn't back down a single step, and Kousaka was the same.

If this is how it is, the rest will come down to stubbornness, he thought. Whoever gives in to this cold first. A test of endurance.

He looked around the inside of the container again. There were several air vents on the walls to prevent condensation, and the light from them made for an imperfect darkness inside. Not much risk of suffocation at least, he thought with relief.

Kousaka sat on the ground. The floor was boarded, but cold enough to make him feel like he was sitting directly on ice. The rusty container was an agonizing place for the germaphobe Kousaka, but the chill brought by the snowstorm broke apart that discomfort to an extent. In this cold, even bacteria would calm down, he supposed.

Sensing Kousaka's intent, Sanagi also refrained from any further talk, and sat down next to him.

This won't take too long, Kousaka felt. It was nearly as cold inside the container as it was outside, like a natural refrigerator. A resolution should come to this test of endurance quickly. And generally speaking, women were more susceptible to the cold than men. She would have to give up first.

It was likely Izumi who locked the container from the outside. Kousaka couldn't think of anyone else who would assist with Sanagi's tricks. And Izumi, who surely saw his late daughter in her, would prioritize Sanagi's life over her will. Even on the off chance Sanagi went berserk and changed plans from negotiation to suicide, Izumi would surely come in to stop her.

And so Kousaka was feeling optimistic. What he failed to account for was the fact that it happened to be a record-breakingly cold day. That cold caused them to weaken quickly. And because of a traffic accident caused by the frozen roads, the only road leading to the location of the abandoned house was blocked off, preventing Izumi, who had gone out to get gas, from returning.

The first few hours, he was just constantly thinking about the cold. The chilly air and wet floor together sapped his warmth. Kousaka kept rubbing together his hands and feet and did stretches, trying to slightly slow the cooling of his body.

But past a certain stage, the cold itself stopped being a problem. Gradually, he instead began to feel a more fundamental discomfort resembling pain. A dangerous sign. His body slowly numbed and wouldn't move as he willed it. His heart beat at a strange rhythm, and his arms and legs were so cold, they didn't feel like his own.

Kousaka kept silent for a long time. He considered that in this sort of endurance test, you'd be at a disadvantage if you opened your mouth first. It was like confessing that you were getting weak.

He figured Sanagi was silent for similar reasons. And that had been true for the first few hours. She kept a refreshed face to show she was handling it fine.

Kousaka noticed Sanagi's breathing was strangely faint about four hours after they were locked in the container.

He got worried and called to her.


There was no reply. "Are you okay?" He shook her shoulder, but her hand sluggishly pushed his away.

When her hand touched Kousaka, he shivered. That hand was so cold, it didn't feel like it was a human's.

Kousaka put his hands around hers to warm them. Though not as much as Sanagi's, his hands were cold too, so it was mostly meaningless.

"...Hey, Sanagi, won't you give up soon?"

"No," Sanagi replied, just barely audible.

Kousaka sighed deeply.

"All right. I admit defeat. I won't take the treatment. I won't kill the worm. So let's get out of here. At this rate, it'll soon be too late for us."

Then Sanagi let out a giggle. It had a desperate feel to it.

"That took surprisingly long. I didn't think you'd hold out so long."

"Now let's get out already. How do we open the door?"

Sanagi was silent for a while.

Then she spoke.

"...Um, well, in my initial plan, Izumi should have come back here to let us out an hour ago."

Kousaka blinked. "What do you mean?"

"I guess something happened to him. Maybe he got caught up in an accident. And if Izumi isn't here, that means the door won't open. Well, well."

"So, you mean... if we're not lucky, we might never be able to leave?"

Sanagi didn't confirm or deny it. Which was to say, it wasn't implausible.

Kousaka put his hands on his knees, stood up, and with a running start from the other wall, kicked the door. He tried it dozens of times, but the container door didn't budge. He slumped against the wall, exhausted, and fell apart onto the floor. Counting on a sliver of hope, he took out his smartphone, but it was indeed still out of range.

Then there was a thud. A moment later, he realized it was Sanagi falling to the floor. Kousaka fumbled through the darkness and lifted up Sanagi's body. Then he called to her to confirm she was still conscious. "Sanagi. Hey, Sanagi."

"I'm fine. I just kind of stumbled."

She must have been fading fast. Her shivering had calmed down, but that only signified that things were getting worse. Her body was starting to give up on creating heat. If she fell asleep, she'd definitely die of hypothermia.

Kousaka embraced Sanagi, and she whispered "I'm sorry" into his ear. He could still feel a faint warmth in her breath.

Then there was the sound of something hitting the floor. It caught the moonlight coming in through the air vents and dimly shined. It was an oil lighter. Sanagi'd had the lighter she used to light her cigarettes in her coat pocket.

Kousaka considered burning an article of clothing to get warm, but as the walls and floors were wood planks and it was uncertain how effective the air vents actually were, they couldn't make too big of a fire. Kousaka lit the lighter and put it in the middle of the floor. An orange light illuminated the container, and large shadows of Sanagi and Kousaka appeared on the wall. It was a small flame, but an unbelievable difference.

Then Kousaka held Sanagi tightly again. There didn't seem to be any other options besides trying to slow the loss of temperature as they waited for Izumi.

Sanagi continued her faint, irregular breathing close to Kousaka's face. As he listened to her breathing, Kousaka nearly forgot he was trying to lose his affection for her. The worm in his body seemed to delight in the situation of the two hosts hugging. Their joy got to Kousaka as well, and temporarily made him forget the cold.

Indeed, it would be regettable to lose this happiness. Kousaka, too, had to admit that. But that was the worm's strategy. If I succumb to its temptation now, I'll be doing just what it wants. I have to stand my ground here.

While Kousaka dealt with his internal discord, Sanagi whispered from within his arms. "Hey, Mr. Kousaka."


"Can I believe what you said? Is it true you won't kill the worm?"

"No, I lied," Kousaka replied honestly. There was no reason to deceive her now. "I just did it to fool you and get us out."

"...I knew it. You're such a liar."
"You can't apologize. I won't forgive you."

Immediately afterward, Sanagi's body, which had been limp as a puppet with cut strings, swelled with energy. She grabbed Kousaka's shoulders and pushed him to the floor. Completely caught off-guard, Kousaka didn't know what was happening at first. Before he could understand, Sanagi's lips pushed against his.

One of their bodies hit the lighter and knocked it over, and the flame went out as it touched the wet floor. So Kousaka didn't know what kind of expression she had after their lips parted.

After separating himself from Sanagi at length, and relighting the lighter while catching his breath, he glared at her.

"Maybe now our worms have moved to the sexual reproduction stage," Sanagi said with a look of triumph. "And maybe they'll spread more and more, and be able to control you more strongly." Then she put on a smile as a bluff.

"...It's futile. I'll take the medicine before that happens."

"Nope. I won't let you drink any medicine. I'll get in your way."

Then Sanagi tried to pin down Kousaka again. But her stamina had already hit its limits from the earlier struggle. She collapsed in front of him, and didn't move. Kousaka hurriedly lifted her up, but her eyes were hollow, and every breath seemed like it could be her last. When he embraced her, he didn't feel any warmth, like he was holding a doll.

What a foolish girl. Kousaka bit his lip.

He prayed for Izumi to come any moment now. But Izumi appeared there nearly two hours later. By that time, Kousaka and Sanagi had both lost consciousness. When Izumi opened the container door, he saw them huddled up together, lying on the floor.


The two were taken to Urizane's clinic and hospitalized for a few days. Kousaka recovered enough to walk on his own by the next day, but Sanagi needed five days to recover that much.

The second day of hospitalization, Izumi visited Kousaka's hospital room and apologized for putting their lives in danger. The snowstorm had caused a three-car pileup that included a bus and blocked off the road, which is why he was so late getting back to them. Due to a miscommunication, Izumi was under the impression Sanagi had some means of escaping the container by herself. If I'd known that wasn't the case, I would have called the police or fire department to send help, Izumi said with much regret. Don't worry about it, Kousaka said. Sanagi and I are still alive in the end, so there's no point in blaming anyone.

"You wanted to make Sanagi give up completely, didn't you?", Kousaka asked.

"Yeah, more or less," Izumi quietly affirmed. "If I pulled her away by force, that'd just give her more attachment, right? So I thought I'd let her resist until she was satisfied."

"What did you intend to do if Sanagi persuaded me?"

"Don't ask me. Hadn't imagined that possibility. I trusted you a whole lot," Izumi said jestingly.

The next day, Kousaka told Urizane about what happened in the container. And he went silent for a while with a scowl.

"Do I take that to mean treatment has gotten harder?", Kousaka asked.

"No, that's no concern. It's just..." Urizane closed his eyes tight, then slowly opened them over a few seconds. "To think she was brooding over it to such an extent."

Then Urizane explained the process of treating the worm. After about a month of taking deworming medicine, there was a half-month rest period - this cycle was to be repeated again and again. He said it would probably be about three to six months before the worms were completely gone. Sanagi would be taking the same treatment.

The day to leave the hospital came. Before leaving the clinic, Kousaka was given the chance to say some parting words to Sanagi.

He knocked on Sanagi's door, waited five seconds, and entered. She wore a pale blue hospital gown and was reading a thick book in bed. On her head were the headphones Kousaka had once given her.

When she noticed Kousaka there, Sanagi closed the book, took off the headphones, and looked at him lonesomely. She seemed to suspect he was here to say goodbye.

"I'll be getting dismissed from the hospital today," Kousaka reported, his eyes turned away from Sanagi. "I don't think I'll see you again for a while."

Of course, I probably won't see you after the treatment is complete either, Kousaka thought. So this might be our last goodbye.

Sanagi seemed deeply aware of that as well.

She didn't reply, only hanging her head in silence.

Soon, Sanagi started to sob.

It was a very regulated sob, like a drizzle wetting her skin.

Kousaka put his hand on Sanagi's head and gently stroked it.

"After the treatment, I'll come see you again." Kousaka permitted himself a consoling lie. "If the worms in our bodies die, and we can still like each other - then we'll formally be lovers."

Sanagi wiped her face with her palm and looked up. "...Really?"

"Yeah, I promise." Kousaka smiled.

Sanagi extended her arms toward him, leaning off the bed. Kousaka held her skinny frame and said:

"It's okay. I'm sure we can get along without the worm."

"...You promise, right?", Sanagi asked through tears.

And like that, the two parted. Leaving the hospital room and clinic behind, Kousaka saw his first blue sky in some time. The bright sunlight reflecting off the piles of snow stung his eyes, and he squinted. The air was chilly; he felt like he was waking up.

My days in the infirmary are over, Kousaka thought. It's a good time for me to wake up from my dream. I can take it slow. Just a little bit at a time, I'll have to get myself used to this worm-eaten world.


Chapter 8: An Epidemic of Absence

The snow covering the town gradually melted, and beside the lingering snow dirtied by mud, fuki plants showed their faces, signaling the arrival of a new season. The cheerfulness of spring filled the air, and a sweet floral smell drifted through the residential district. People took off their thick coats to wear jackets, savoring a sense of liberation that had been missing for some time.

The cherry trees in this town bloomed at the end of April. Depending on the year, their optimal viewing time could be as late as Golden Week. As a result, cherry blossoms weren't symbols of meetings and farewells to the townspeople. Instead, they were like flowers that, after completing a change of environment and taking a breath, appeared to suggest the future.

It was the first day of a three-day weekend. Kousaka lazily walked the long hilly road through the residential district.

There was construction being done in several places around town. Some buildings were being constructed, whereas other buildings were being dismantled. There were areas with road repair work, and areas with power line work. It's like the whole town is being reborn, Kousaka thought.

"Kousaka, when were you going to move, again?", asked a girl walking beside him.

"Next week," he replied.
"That's sudden. Why at a random time like this?"

"Thinking about it, commuting was pretty inconvenient here. I decided I should move somewhere closer."

It was a girl a coworker had introduced to him, named Matsuo. She was two years younger than Kousaka. Her always-lowered eyebrow-ends gave off a gloomy impression, but if you looked, she had pretty good facial features, and a wholly refreshing smile. She had worked part-time as a student until she was made into official employee, and continued with her job since.

This was Kousaka's third time having an outing with her. It had been less than a month since they got to know each other, but Matsuo showed affection for Kousaka since the first time they met. Kousaka also felt like he could naturally relax around her.

Once they talked, they found they had a surprising amount in common. For instance, germaphobia. Until just two years ago, she had washed her hands a hundred times a day, changed clothes five times a day, and took three-hour showers. Thanks to perseverant treatment, she was now able to live a normal life, but at its worst, she couldn't even leave the house. When Kousaka casually brought up germaphobe-related items like disinfectant and air purifiers, Matsuo's eyes shined and she spoke about them.

Book and music tastes, feeling distanced from work, lacking interest in social problems. In many respects, Kousaka and Matsuo's opinions matched. It was the natural flow of things for them to become friendly.

The two kept walking aimlessly, talking about movies they'd watched recently. As they came to the path along the river, the topic changed to fishing. Matsuo spoke about memories of her father taking along to go ocean fishing.

"Oh, yeah, I got food poisoning from that once," Matsuo recalled.

"It was when I was eight or so. We made sashimi from a greenling we caught at home, and ate it as a family. It was really tasty, but late that night, I suddenly got a really bad stomachache. I really wondered if I was going to die. And I was the only one affected - my dad, my mom, and my little sister were totally fine. It was awful."

"Anisakiasis, I bet?", Kousaka said with a wry smile. "That even makes grown-ups writhe in agony, so it must have been hell for a kid."

"Oh, you're so knowledgeable!" Matsuo clapped her hands in admiration. "Yes, it was the doing of that foul Anisakis. Do you go fishing too, Kousaka?"

"Nah. Never even been to a fishing hole."
"Then do you eat lots of raw fish?"

"I had an acquaintance who knows all about that kind of thing. I'm just repeating it from her."

"Oh, is that it." Matsuo nodded, then asked to dig deeper, "An acquaintance? Is she a friend?"

"No, a little different from a friend."

"Then what? A girlfriend?"

"About five months ago, I had a part-time babysitting job. I heard it from her."

"Babysitting..." Matsuo looked increasingly suspicious. "Kousaka, you don't seem like you'd be great with children."

"Yeah. But there were reasons I had to take the job."

"I... see," Matsuo affirmed ambiguously. "Even so, isn't it rather rare to find a child who'd tell you about Anisakis?"

"I guess so," Kousaka said. "I've only met the one, myself."


In less than four months since he started taking the deworming medicine, Kousaka experienced such great changes that you might as well say he was reborn.

First, his germaphobia was cured. The disorder that was so firmly rooted in the person Kengo Kousaka was gone like it never existed a month after treatment started. It really was instant. Like a stomachache or mouth ulcer: you can think of nothing else before it's cured, but once it's gone, you can hardly remember what it was like.

When he paid attention, he realized he was using the same towels for several days, and was fine going from getting home straight into bed. He didn't think anything of being shoulder to shoulder with other people, and could grab onto straps on the train if necessary.

Once the bottleneck of his germaphobia was cured, the rest proceeded steadily. He easily settled upon a new job. Looking through a site geared for people who were trying to get back to work after rehabilitation, as if by coincidence, his eyes went straight to a highly favorable job offer. It was a recruitment for web programmers at a web design company, and the programming languages listed as requirements were all ones he was an expert in. Kousaka took the offer, submitted some of his code, and left the rest to flow. He didn't have any hopes at all, but by next month, he was a full-time employee at the company. Things moved so smoothly as to make him worried someone was stringing him along.

As he noticed once he began working, Kousaka spending his free time making malware really helped develop his programming skills. It wasn't that he learned the specific knowledge, but rather that he established the right thought process for programming. He became valued at his workplace. It certainly wasn't the easiest job, but having found a solid place to be gave him great joy.

Kousaka slowly but surely regained confidence, to a level appropriate for his age. People around Kousaka mistook his calmness that stemmed from resignation as composure from rich life experiences, and were convinced he was a superb person. They saw his frequent job changes as proof of his faith in his own abilities. Every element miraculously worked as a positive. Just a month after joining the company, he'd made friends to have a drink with after work, and himself nearly forgot that until a few months ago, he was completely unfit for society.

And yet sometimes, he suddenly felt a boundless void within himself. Said void was in the shape of a girl. When he dozed off at his desk, when he walked the same roads he had once walked with her, when he saw things he associated with her - headphones, blue earrings, oil lighters. At any such opportunity, Kousaka was made to recall Hijiri Sanagi.

But that was all over. Sanagi had surely long forgotten the days they spent together, and had started on her own true life.

That was probably something to be celebrated, Kousaka thought.

In the last third of March, Kousaka, fully adapted to work and convinced of his cured misanthropy, discovered that even freed of the worm's effects, he as of yet loved Sanagi. That part which he'd expected to be the first to change right after treatment began was the one thing about him that hadn't changed a bit.

Kousaka felt deep confusion. Wasn't the love between Sanagi and I a sham brought about by the worm? Why has my germaphobia and misanthropy been cured, but not my "lovesickness"?

Maybe I've had a terrible misunderstanding? Maybe the consolation I gave Sanagi when we parted to pacify her was right on the mark. It was likely the truth that the worm had the power to make its hosts fall in love. But even without that - that is, without the worm - had Sanagi and I been able to love each other from the start? Maybe I just failed to realize that, and after hearing about Professor Kanroji and the Hasegawas, came to cast doubt on everything and distrusted my own feelings?

His heart beat fiercely, urging him on. Almost unconsciously, Kousaka called Sanagi. The call sound played. He counted. One, two, three, four... at five, the call gave up and ended.

Kousaka put his hand to his chest and took a deep breath, calming his rapid heartbeat. There's no rush. She should call back eventually.

But a whole day passed with no contact from Sanagi. Afterward, Kousaka called five times and sent three emails, but with zero responses.

He considered going to Sanagi's house directly. It had been a month and a half since he last visited Urizane Clinic. He'd been given plenty of medicine, and there was no sign of his symptoms returning, so he had no reason to go. But while he hadn't considered it when visiting before, if he went to the clinic and said "I want you to let me meet Sanagi," would they have a reason to refuse him?

Kousaka examined the pros and cons. But his swelling feelings, after a certain point, began to rapidly shrivel up.

Now that he thought about it, there could only be one reason why Sanagi wasn't responding. One or two, perhaps, but she couldn't have not noticed five or six attempts at contacting her. The fact that trying this again and again didn't get any reply meant that she was intentionally ignoring Kousaka's attempts to contact her.

Sanagi must be trying to forget about me, Kousaka concluded. Maybe her deworming had also succeeded, and she was able to escape the worm's control. And once she regained her normal thoughts, not a shred of affection for Kousaka remained. It was ironic, but that was probably what it was.

It didn't take too long for Kousaka to come to terms with that. Luckily, he had plenty of work he had to do. Instead of worrying about Sanagi, he focused himself on those tasks. In doing so, he got to know Matsuo, and the hole in his heart was slowly filled with things to substitute.

This way of life is the most proper and reasonable, Kousaka told himself. My days with Sanagi were like a dream in fading consciousness, a kind of phantasmagoria. Indeed, they were more beautiful than anything. But in the end, just a dream. If I try to stay there forever, I'll just be dying while I live. What we should be chasing after is happiness with its feet on the ground, happiness for the living.


He was brought back to his senses, and nearly dropped the glass in his right hand. What was I doing again?, Kousaka wondered. Right, I remember. I was drinking with Matsuo. We were walking through town together and decided to go into an Irish pub we spotted. I must have been nodding off from drunkness and fatigue.

"Ahh, sorry. I was spacing out." Kousaka firmly rubbed his brow.

"You were doing that for a pretty long time," Matsuo said with a laugh. "It looks like it's almost closing time. Do you want another drink, or not?"

Kousaka looked at his wristwatch and thought.

"I think I'll call it for today. Or have you not had enough, Matsuo?"

"Oh, no." Matsuo shook her head forcefully. "I'm probably too drunk as it is."

"It does look that way," Kousaka affirmed, seeing the faint red in her face.

"Yes, I'm drunk enough that you look a little cool, Kousaka."

"That's a serious illness. Better get home and rest."
"Right. I'll do that."

With that, Matsuo picked up the glass in front of her and poured it all down her throat. Then she met eyes with Kousaka, bent her head down, and smiled playfully. But Kousaka observed that her eyes, though very faint, had a tinge of disappointment.

Maybe my reply wasn't what she was hoping for, Kousaka thought to himself. Maybe Matsuo wants to take our relationship to the next step. She's showing enough signs that even someone who can't take a hint like me can tell.

If I know that, why won't I respond?

Maybe somewhere in my heart, I'm still holding on to Sanagi?

After leaving Matsuo, Kousaka headed not for the train station, but retraced his steps to another bar to drink some more. He couldn't explain to himself why he did that. Maybe because if he went back to that room, like it or not, he'd remember being with Sanagi. Maybe the reason he was hesitating to advance his relationship with Matsuo, too, was because he couldn't permit outsiders into the room he'd been with Sanagi in.

He felt he finally understood why he was in a hurry to move. How pathetic, Kousaka laughed self-derisively. I want to think I've become a proper human, but deep in my heart, my crush on a 17-year-old girl goes on.


He missed the last train, so he took a taxi home. He got the money out of his wallet without really counting, gave it to the driver, and took the change. When he got out of the car in the residential district, the thick smell of spring flowers carried on the night wind tickled his nose.

With an unsteady walk, he climbed up the apartment stairs. After unlocking the door to his room, he fell collapsing onto the bed. These spring nights were warm, the mattress was soft, and the sheets were cool. He let his consciousness drift away.

At first, he thought his ears were ringing. But as it repeated again and again, he realized it was the sound of the intercom. He thought it had turned morning while he nodded off, but when he sat up and looked out the window, it was still night. He looked at the clock, which had just turned 2 AM. Who could it be at this abnormal hour...? Just as he had that question, he remembered something very similar that had happened before.

His drunkenness and drowsiness cooled in an instant. He lept up and went to open the front door.

His prediction was correct. Standing there was Izumi. With one hand in the pocket of his worn suit, he rubbed his unshaven beard with the other. He wasn't wearing his usual drab coat.

"Hey. You been doing well?"

"Izumi?", Kousaka asked, dumbfounded. "What could you be here for?"

"Is it okay if I come in? Or has your germaphobia not cured yet?"
"No, I don't really mind if you come in..."

Izumi took off his leather shoes and entered the room.

"Want some coffee?", Kousaka asked.
"No, I'm fine."

Izumi looked around the room. Since Kousaka was just about to move, it was awfully barren. There was nothing other than a pile of white cardboard boxes in the corner and minimal furnishings. His work chair and desk, an empty bookcase, coat hangers, the bed. Izumi thought for a bit, then gently sat on a cardboard box.

Kousaka sat in the chair and asked:

"If you've come here, then something related to the worm must have come up, more or less."

"Correct," Izumi replied without budging an eyebrow.

"Has there been some problem?"

"I'd actually like to ask you - anything to mention?", Izumi asked back. "Any strange changes happen lately?"

"No, no real outstanding changes. I'm recovering quite well." Kousaka suddenly noticed he still had his wristwatch on, so he took it off and flung it onto the bed. "Thanks to you, my misanthropy has been cured too. It seems all the worms in me have died off."

"That's wrong. Your worms haven't gone yet."

A silence fell between them.

"...What are you talking about?", Kousaka said with a stiff smile. "As you can see, my germaphobia's gone. I successfully got a new job, and my human relationships are going smoothly. There's no trace of the worm's effects left."

Izumi shook his head. "It's just a lull state. I don't know why, but the worms in your body seem to have a resistance to medicine. It's not like I've checked, but I can't think of anything else. They've temporarily weakened for now, but if you stopped taking the medicine for a while, they'd probably come back right away." Then he suddenly grinned. "And that's a very lucky thing."


"I'm saying you should be grateful your worms have such powerful survivability."

As if enduring something, Izumi took a deep breath, and slowly let it out.

Then he informed him.

"Except for you, deworming medicine has been extremely effective on those infected with the worm. And when the worms in their bodies died... their hosts, too, chose death."

Kousaka's expression stayed frozen. Not a word came out of his mouth.

Izumi continued.

"Professor Kanroji and Dr. Urizane had the same opinion about the worm causing the infected to commit suicide. They thought that once the number of worms in the host's body passed a certain number, they couldn't bear living in human society anymore and accepted death. Well, it was a reasonable guess. Even if it weren't for those two, you might think so. ...But there was a fatal mistake in that thinking. We were thinking with the assumption of "suicide equals abnormality." That was the trap we fell into.

"As research continued, a number of facts came to the surface. This parasite's final host is humans, sure, but it doesn't seem it can infect just any human. In fact, it can't infect most humans; even if it gets into their body, it's quickly shut down by the immune system. But in rare cases, there's people like you with bodies that not only don't exterminate the worm, but firmly preserve it. Like they're actively accepting infection.

"This is getting into my own subjectivity a little, but... maybe the worm doesn't have any such power to make the hosts kill themselves. Sure, it isolates the host, but maybe that has nothing to do with their death. In fact, there's one new fact Dr. Urizane's research found. That the worm has the ability to suppress the host's negative emotions. Anger, sadness, jealousy, hate... any negative emotions that occur in the host can be weakened by the worm. I don't know the detailed workings, but Dr. Urizane said it might be that the worm can selectively consume the enzymes needed to create nerve signals. If that theory's correct, then we could explain it as the worm feeding on its host's anguish. Thus it probably isolates its host from society to provide it plenty of anguish. Guess the stress of everyday life isn't filling enough.

"So then I came up with this hypothesis. Maybe the infected, before the worm infected them, were always people with souls prone to sickness - to be frank about it, people with a strong desire to die, or suicidal thoughts? What if the ones the worm could make into hosts were people who'd kill themselves if they were left alone?

"With that theory, a lot that hasn't sat right before suddenly makes sense. The majority of people can't provide enough anguish to sustain the worm's life. Even if the worm is ignored, it'll be weak, and die from an immune system attack. On the other hand, the bodies of people who are constantly charmed by death with more anguish than they can handle, they've gotta be better than the worm could ever ask for. Some ticks that infect humans eat excess sebum and keep balance in the skin, so it's kind of like that. They eat excess anguish to keep a mental balance. ...So those bodies don't exterminate the worm, they accept it. They get incorporated like an organ to handle all that anguish that the host can't handle alone. The host and the worm form a mutually-beneficial relationship.

"So, what happens if you try to exterminate a worm like that with medicine? All that anguish it was taking care of has nowhere to go, and the host is hit with it again all at once. They got so naive with the worm protecting them, they don't have the strength left to endure. They lose what was letting them live longer; nothing's left to stop their longing for death.

"We were convinced the deaths of the infected were caused by the presence of the parasites. But the reality was just the opposite. Their death was caused by the absence of parasites. That's my conclusion."

Various things Kousaka heard from Sanagi surfaced in his mind like flashbacks.

"...Thus, making the immunosuppressive system work is linked to bettering immunity-related diseases. But apparently, these regulatory T cells are brought about by the existence of "parasites approved by the host." So in essence, the absence of parasites, an extremely clean situation, results in an increase in modern day allergies and autoimmune diseases."

"Also, D. nipponicum don't abandon their partners to the last. Once D. nipponicum join together, they never let go of each other. If you try to tear them apart, they'll die."

And cysticercosis - a disease that first occurs when bladder worms die in the central nervous system.

The clues had been there all along.

We were being given life by the parasites - and we never should have let go for a moment.

"Sanagi -" That was the first word out of his mouth. "What happened to Sanagi?"

"She was the first victim," Izumi said. "Hijiri Sanagi was the first to experience the effects from the absence of parasites. One morning, Dr. Urizane got worried that his granddaughter wasn't waking up, so he went to her room and found her lying on the floor, unmoving. There were signs she'd downed a ton of sleeping pills and alcohol. That was about half a month ago."

The world fell out from under him. His vision blurred, and his ears rang loudly.

But Izumi's next words pulled Kousaka up from his fall into hell.

"But don't worry. Hijiri Sanagi's not dead yet. Her attempt failed. She was a little too excessive - her strong desire to die backfired on her. She took so many pills and so much alcohol, so she threw up before either took much effect. Or else maybe she got afraid in the middle and threw it up herself, but either way, she was spared. Although..."

Izumi was stuck on what to say, and looked toward the window to think. Kousaka looked out there too, but there was nothing notable to look at. Just darkness.

Eventually, Izumi opened his mouth.

"After getting minimal treatment at the clinic, she was transferred to a proper hospital. Her life didn't seem in danger for the time being, so Dr. Urizane and I were relieved. But Hijiri Sanagi's suicide attempts had only just begun. She was like a canary in a coal mine."

Kousaka took the initiative to ask: "The other patients - did the Hasegawas behave similarly?"

"They did," Izumi nodded. "A week after the incident with Hijiri Sanagi, we got a call from Yuuji Hasegawa. "Satoko Hasegawa has committed suicide," he said, then hung up. We didn't know what was going on. The next day, we decided to head to his house to ask for details, but we were too late. Yuuji Hasegawa had already followed after his wife. The two had expired huddled up together. And while we were discovering the Hasegawas' suicides, Hijiri Sanagi vanished from her hospital room."


"Yeah. She left a note that just said "thank you very much." We put out a search order, and I've been looking around myself for days, but we haven't found Hijiri Sanagi. I thought she might have come to your place, but I guess that was wrong. ...Where could she have gotten to?"

Then Izumi fell silent. His face looked tired. It seemed he'd been beaten down by fatigue, powerlessness, and all sorts of other emotions.

"I'm so exhausted," Izumi said with a sigh.

"In the end, what we were doing was completely off the mark. We didn't save the patients, we actively drove them to death. We just had to meddle with something that was fine left alone. What a comedy show. Dr. Urizane's spirits are in the dumps, like he's been stunned into numbness. He might just kill himself before his granddaughter."

After a laugh, Izumi stood up sluggishly.

"It's selfish, but... as of today, I'm gonna be leaving Dr. Urizane. Doubt I'll see you again."

Izumi turned his back to Kousaka.

Kousaka called to him.


"What?", Izumi said without turning around.

"Please, don't die."
"...If you're worried about that, I'm really done for."

Izumi's shoulders shook with a chuckle.

"So long. Get on well with that worm. Like it or don't like it, it's an important part of you."

With that parting remark, he left.

A suicide attempt. That was the real reason Sanagi hadn't responded to his calls and emails. By the time Kousaka called, the worms in Sanagi's body had already died off, and she was fighting an encroaching longing for death. Or maybe she was steadily preparing for suicide. Either way, that was what was filling her head, and she couldn't afford to think about anything else.

So Sanagi's lack of response wasn't because she hated me - that was Kousaka's honest first impression, before thoughts of ensuring her safety. It was imprudent, but that was what Kousaka delighted over first.

Ultimately, this happiness I'm feeling now is everything, Kousaka thought. I love Sanagi. There's nothing more definite than that. The worm and our ages don't change that. If this feeling is a lie, then I'll keep being deceived until the day I die.

After relishing that happiness, Kousaka considered the whereabouts of the missing Sanagi. The locations of special interest to her were very limited. Thus, the options were naturally narrowed down.

Perhaps Sanagi intended to kill herself in the same place her parents did. He heard they had jumped off a bridge in the mountains which was infamous for suicides. It wouldn't be strange if she wanted to jump from that same place herself.

I have no real evidence. But right now, I also don't have any clues that sound better. I need to head there, Kousaka thought strongly.

He called a taxi from his phone. He got in the taxi that arrived ten minutes later and told the driver his destination. The aging driver silently started to drive without an affirmation.

But a whole twenty minutes later, Kousaka said he forgot something and had him turn around. Truthfully, it wasn't something he forgot to take. He just suddenly thought: I should wear the red scarf Sanagi gave me on Christmas Eve.

Even though it was a race against time, he couldn't help but feel it was necessary. It was a kind of prayer. He felt that scarf would serve the role of a red thread that pulled them together.

To say it in advance, that premonition was on the mark.

Maybe it was the worm in his head that secretly told him so.

Back at the apartment, Kousaka raced up the stairs and arrived at his apartment door out of breath. As he put his key in, he noticed the door was already unlocked. He must have forgotten to lock it in his hurry to leave.

When he went inside, he saw light seeping in from the living room door. It seemed he also forgot to turn off the lights. But he didn't care about that. Kousaka entered the room without taking off his dirty shoes, went through the kitchen to the living room,

and there, sleeping soundly, he found Sanagi.


Chapter 9: Parasite in Love

Kousaka woke up to the smell of coffee. Soft morning light came in through the window.

He slowly looked around, still lying in bed. There were two mugs together on the table, with faint vapor visible. From the kitchen came the smell of buttered toast and cooked bacon.

Listening close, mixed in with the morning chirps of birds, he heard Sanagi whistling.

It was that kind of morning.

They put two cardboard boxes together and used them as a table to have breakfast. From a distance, the white cardboard boxes could look a bit like a table painted white.

There was hardly any conversation between them. A radio on the table played intermittent music. Kousaka didn't know what song it was, but it definitely had piano in it. Occasionally he heard a fragmentally nostalgic melody, but if he tried to listen to the specifics, the melody seemed to get quiet and run away.

After breakfast, the two took showers and prepared to head out. All Sanagi had besides pajamas was her uniform, so she wore that. Kousaka got a zero-personality shirt and chino pants out of the closet, but as he was about to change into them, Sanagi stopped him. "Hold on a sec."

"You know how when we first met, you were wearing a suit despite not having a job? I wanna see that again."

"Sure, but why?"
"Because I like you in a suit. Got a problem?"

Kousaka shook his head. "It's no problem. And I am working now, so I won't feel too guilty about it either. I'm a little worried how it looks to others with me wearing a suit and you wearing a school uniform, though."

"It's fine. If anyone asks, we'll just say we're siblings."

I guess you're right, Kousaka readily agreed.

After changing, the two left the apartment for a walk. A peaceful sunlight appropriate for a quiet Sunday shone on the residential district. The cherry blossoms were apparently starting to fall, as pink petals piled up on the road. The sky, as if to complement the color of the cherry trees, was a modest light blue. Little clouds that brought to mind pieces of fluff floated through that sky.

The two held hands, in a way that seemed like neither went first, and walked.

They went into a used bookstore at the end of the shopping district outside the train station, and spent a while there. The store was cramped, and smelled of musty old books.

Kousaka became fond of an unusual encyclopedia he spotted, and after some slight hesitation, he purchased it. It was effectively an "encyclopedia of encyclopedias," listing all the different types of encyclopedias in the world.

Then the two went to a bakery on the corner of the street, got sandwiches, and walked as they ate. They were loaded with ingredients, so with each bite, lettuce and onion would fall out. Seeing Kousaka clean up the sauce around his mouth with his finger, Sanagi giggled.

"I couldn't imagine you doing this before, Mr. Kousaka."

"Guess so. Eating while walking, or touching old books, I'd only ever do it in these past three months," Kousaka said, wiping breadcrumbs off his hands. "But Izumi says once the worms get healthy again, my germaphobia will apparently return. Once that happens, it's dubious if I'll be able to keep a job."

"Huh," Sanagi said with disappointment. "Well, you'd better enjoy a lot of impure things while you can."

Kousaka grinned wryly. And he took back Sanagi's hand.


Let's rewind a bit.

When Kousaka found Sanagi sleeping in his bed the night before, he first wondered if it was a hallucination of his. It was just a mistake; the next time he blinked, she would be gone.

So he kept his eyes wide open. He decided to take in that illusion for as long as he could. Soon, his eyes dried and started to tear up, so he unwillingly closed them. When they opened, the illusory Sanagi was still there.

He closed his eyes again, rubbed them for ten seconds, and reopened them.

Yes, Sanagi was there.

"Sanagi," he said out loud.

When he spoke, Sanagi's body twitched. Soon, she slowly sat up and met eyes with Kousaka. Then as if to hide herself from him, she pulled the blanket up to her chest, and lowered her head with embarrassment.

Kousaka's feelings were temporarily numbed by shock, so he couldn't be surprised or happy.

"You aren't a ghost, right?", he asked.

"Who knows," she said with upturned eyes. "Want to test?"

Kousaka timidly approached, and reached out to touch her cheek. There was the feeling of human skin, and warmth. To further push the point, Sanagi put her right hand on his. There was definitely the feel of human skin there, too. She really existed.

Kousaka put his arms around Sanagi's back and hugged her. Sanagi accepted it wordlessly.

"Why..." He was too emotional to properly put any words together. "Why are you here? Is your body okay? Aren't the worms dead?"

"Don't ask me all at once," Sanagi laughed nervously. "Ask one at a time."

Kousaka gently parted from her and asked, "Is your body okay?"

"Hmm. To tell the truth, it's still not too healthy," Sanagi said. "But considering how much medicine I took then, it's a miracle it turned out this well."

She poked around her stomach area.

"My memories got dicey while I was in a coma, so I don't remember much about the part where I decided to kill myself. But I do vaguely remember throwing up the medicine of my own will. I'm sure I must have come back to my senses just in time. The doctor said if I had thrown up a little later, there'd be nothing they could do."

"So that's it..." Kousaka let out a big breath. "Well, next, where have you been and what have you been doing after you ran from your hospital room? And why did you vanish in the first place?"

"There was something I wanted to do, so I hid out in our clinic. I always used to hide when I didn't want to go to school, so there's a hiding place only I know." Then Sanagi shrugged. "But that's not really what I want to talk about. Isn't there something more important to ask?"

"...What happened with the worm? Didn't you kill them off with the medicine?"

"Yeah. It seems like all the worms that were in me are dead."

"Then why -"

Sanagi grinned.

"What's inside me now are the worms that were in your body, Mr. Kousaka."

"My worms?"

"That day, in the container, I forced you to kiss me, right?" Sanagi turned her eyes away shyly. "At that moment, some of the worms from your body transferred to mine, copulated with my worms, and birthed resistant parasites. That's what let me just barely survive. Your worms saved my life, Mr. Kousaka."

Kousaka closed his eyes and thought, then sighed.

"In the end, I guess you were right about everything, and I was wrong."

Sanagi shook her head. "What can you do? It's not like I had any basis to consider the worm important either. In this case, my desires and the reality just happened to match up. Your judgement was definitely proper. And I know the reason you refused me was for my sake."

"You're way overestimating me. I'm not that great of a person."

Kousaka gave her a weak smile, then said formally:

"Thanks for coming back. I'm really happy."

"Same here. Thanks for leaving a place for me to come back to."

Sanagi slightly lowered her head, and her lips formed a smile.


A blue car was parked by the entrance to the park. Many cherry tree petals were stuck to the hood and windshield, greatly interfering with visibility. Looking through the passenger-side window, there was a man sleeping soundly in the driver's seat.

Kousaka looked all around, but didn't see any cherry trees. The wind had probably carried them here from inside the park. It was a windy day, after all. Regardless, walking around aimlessly almost made him forget about the wind. Maybe because there were no changes in the way it blew.

A few minutes after entering Mizushina Park, the two got on a path lined with cherry trees on either side, and after walking a bit, they stopped.

It was a sheer spectacle.

The petals were pouring down like snow.

Blown around by the wind, the treetops swung up and down, making petals fly up into the air one after another, glittering white in the afternoon sun.

The two were overwhelmed by the sight for a while. The cherry trees before them were being blown around so forcefully, likening it to a snowstorm would hardly be an exaggeration. In contrast to the dizzying scene, the park was enveloped by a bizarre silence. The sound of the wind like white noise, and the rustling of the trees. That was all there was. Visitors who came to view the trees were sparse, so there were no blue sheets to impair the view either. There was a bigger park nearby, so everyone was probably going there instead.

Kousaka reminisced. When the two of them first met, this park was covered in snow. Sanagi stood by the lake, feeding swans. At that time, her hair was dyed silver, she wore a short skirt, and she was smoking.

Somehow, it felt like something from the distant past. And yet it hadn't been half a year since then.

Once they were tired of walking, the two sat down on a sloped lawn. And huddling up in the shade of a tree, they watched the cherry tree snowstorm, and listened to the wind.

At the bottom of the slope, they saw the lake. The water was covered with white flower petals, looking almost as if it were frozen over and covered in snow, so you could just walk across.

Then Kousaka noticed a single swan casually swimming in the lake. He looked again and again, but it was no duck, it was a swan. Maybe it had been left behind by the flock? But the swan didn't show any sign of lonesomeness, elegantly swimming among the raft of flowers.

That unrealistic sight reminded Kousaka of a child using toys to make a doll house devoid of order. Like something from an inconsistent dream.

"Hey, Mr. Kousaka," Sanagi said, still leaning her head on his shoulder.

"From the moment I first met you here, I knew it would turn out like this."


"Yeah. ...Do you remember when you first talked to me?"

"I remember it well." Kousaka squinted as if honing his senses. "I thought you were a really unsociable girl."

"I couldn't help that. I'm shy."

Sanagi pouted, then tilted her head a little and looked up.

"When we met, it was under this mistletoe."

Kousaka turned his gaze up. He saw a clearly-foreign plant mixed in around the ends of the cherry tree's branches. When he saw it in winter, it looked so sorry he couldn't distinguish it from a bird's nest, but this mistletoe was now growing verdant leaves.

"People who meet under mistletoe during the Christmas season have to kiss. Did you know?"

Kousaka shook his head. He figured it was probably a Western custom.

"And I'd decided that my first kiss had to be someone I liked. So it was inevitable I'd come to like you, Mr. Kousaka."

"That's some wild logic." Kousaka grinned bitterly.

"I don't really know what I'm saying either." Sanagi laughed, shoulders shaking. "At any rate, I'm saying our love was supported not just by a parasitic animal, but a parasitic plant. All these parasitic organisms are deeply involved in our lives. I think that's what I'm trying to say."

"...I get it."

"Sheesh, if we can't fall in love without depending on parasitic organisms, who knows which of us are the real parasites." Sanagi laughed again.

Then there was silence for a while. The two of them thought about the happy coincidences parasites had brought about for them.

Eventually, Kousaka broke the silence.

"You said earlier people had to kiss under mistletoe."

"Yeah. But only around Christmas time."

"Just look." Kousaka extended his index finger and faced forward. "There's a swan. There's a snowstorm. The lake's frozen over."

"You're right," Sanagi chuckled. "Well, can't argue with that."

Sanagi faced Kousaka and slowly closed her eyes.

Kousaka put a quick kiss on the edge of her lips.

Soon, Sanagi fell asleep in Kousaka's lap. She must have been tired. Maybe the worm was still recovering in her, and wasn't able to fully process the anguish she had.

Kousaka ran his hand through her soft hair. The blue earring hidden on her ear glinted. Even after her hair went back to black, it seemed she still kept her earring on.

Thinking about it, this was his first time seeing her in a spring-like outfit. He hadn't noticed when she was dressed in winter wear, but looking at her body up close, he identified signs that she'd attempted more than just taking sleeping pills. There were some things that looked ancient, and some things that looked recent. Each one of them saddened Kousaka.

I hope she won't have bad dreams, Kousaka prayed.

Cherry petals continued to fall in the park. As they sat in the tree shade, the petals slowly piled upon them.

Before long, the sun descended slightly, and the two were illuminated by dim light coming through the trees. Careful not to wake Sanagi, Kousaka lay down and closed his eyes, and took a breath of the rich spring air, filled with the smell of grass and cherry trees.

I won't be able to experience nature without worry for long. Before too long, my germaphobia will resurge, and I'll hole up in my room again. That thought depressed me a little. But when I think about how this tender feeling I feel when I'm with Sanagi was brought about by the worm, I can't bring myself to hate that parasite of love.

In the end, it had become hazy whether or not we could have fallen in love without depending on the worm. But at this point, I can feel like that's not such a big issue.

Because the worms are an indispensable part of our bodies. We can't think about anything separating ourselves from them. With the inclusion of the worm, I can call myself "me" for the first time.

People don't just fall in love with their heads. They can love with their eyes, love with their ears, love with their fingertips. So then there's nothing strange about how I loved with the worm.

No one can complain about that.


By the time the sky was turning gray, the two left Mizushina Park. They bought food at the supermarket, returned to the apartment, and Kousaka made them a basic meal. After their rather late lunch and post-meal coffee, it was 4 PM.

They were sweating, so they took showers one after the other. Changing into inside wear, they sat together on the bed and looked through the encyclopedia they bought at the bookstore. The shortwave radio on the table placed a foreign news program, but the volume was low, so they couldn't make anything out.

Pale light came through a crack in the curtains. The lights weren't on, so the room was dim like being deep in the forest. Listening close, children could be heard playing in the distance.

After looking through the encyclopedia and closing it, Sanagi spoke.

"I felt like something was missing. But now I know what it was."
"What do you mean?"
"There's no disinfectant smell."

Kousaka blinked.

"Oh, I guess so. Because I haven't been nervously cleaning lately."
"To me, it was that smell that really defined your room."
"You adore the smell of disinfectant?"

Sanagi nodded.

So Kousaka took some disinfectant spray out of a cardboard box, and like he had done daily until a few months ago, he disinfected everything in the room. Sanagi sat on the bed and enjoyed the scene unfolding before her like it were someone putting up Christmas decorations.

Soon, the room was filled with a thick ethanol smell, and Sanagi lay on the bed with a look of satisfaction.

"Yep, it's your room."
"Now that I'm smelling it again, it's an awful smell."

"Really? I like it, it's like an infirmary."
"I think most people would say "I hate it, it's like a hospital.""
"But I like it."

Sanagi put the pillow under her chin, closed her eyes, and sighed.

"I think I could fall asleep like this."

"Hey, didn't you just take a nap earlier?"
"I guess so. But I think I'm exhausted."

Less than five minutes later, she fell asleep.

Kousaka pulled the blanket over Sanagi, and after some hesitation, got in beside her. And he watched her sleep, never tiring of it. At this distance, he could identify each one of her long eyelashes.

It was a fleeting look she had on her face. A look like she'd never once felt her nervousness go away her entire life. Sleeping in the dim afternoon, she seemed unusually brittle and easily-hurt.

First thing in the morning, I'll contact work to cancel my move, Kousaka thought.

I'll unpack these boxes, and with Sanagi, get this room back to how it was.

I'll stay in this town.

And I'll live with her.

While the 5 PM announcement echoed through town, Kousaka slowly closed his eyes.


When Sanagi woke up, Kousaka's face was in front of her. She reflexively jumped back in surprise, eventually realized the situation, took two or three breaths, and lay down again. Her pulse didn't settle down for a while.

The sun had mostly set. She couldn't hear children outside anymore. A warm wind blew through the window, rustling the curtains. Mixing with the disinfectant smell, for a brief moment, it made for a chest-tightening nostalgic smell. She pondered that nostalgia for a while, but before she could identify it, she forgot the smell.

Oh well, Sanagi quietly mumbled. Knowing wouldn't do anything for me.

Then she gently extended her hand and put her fingers between Kousaka's.

I'll always remember this sensation, Sanagi thought.

Considering how much time she had left, that wouldn't be difficult.

Gazing at the faint sunset sky, Sanagi thought.

My life was saved by a kiss with the person I loved.

...How nice would that be if it were true?

When we kissed, some of the worms did move from Kousaka's body to mine, and reproduced with the worms in my body. The same thing had happened in his body. There was no doubt about that.

But the newly-born worms that resulted from that were not the same. The resistant parasites had only been born in Kousaka.

Maybe the worms in Kousaka's body didn't have their resistance to medicine from the start. When my worms and his worms mixed their genes, miraculously, a variation of medical resistance was introduced, and that variation saved his life.

But the same miracle hadn't happened in my body. The worms in my body with no resistance were defenseless, and wiped out by the medicine. And so I lost the organ that processed my anguish.

Now, I'm a husk. I'm already half dead. Like a chicken running around with its head cut off. I have two feet in death, and I'm just waiting to sink.

I survived this long because of my tenacity to meet Kousaka one last time. And now that my wish has been granted, I probably don't have long left. I won't be able to resist the urge to die at the peak of happiness, and I'll take my life.

If I got Kousaka to share some of his worms, there's a chance I could recover, but unfortunately, I don't have any will to do that. I've already written my note.

I intend to carry this to the end.

It was always this way. I was so scared to live, I couldn't bear it. If I didn't take something, I became afraid I would never get it my entire life. If I did take something, I became afraid I would lose it someday.

The scariest thing was that I would never love anyone, and no one would ever love me. If I was going to live a life like that, I thought it would be better to just die as soon as possible. But now that I have learned about love, now I'm more scared than anything to lose it. If I'll have to continue on with this fear, I think it's best to die as soon as possible.

A trend toward death. A self-destructive program. In the end, however things fell, my destination was the same. Happiness and unhappiness are two sides of the same coin, and especially to a coward like me, they have almost the same meaning. Everything serves as an argument to entrust myself to death. That's the person I am.

So I at least want to end it all while the coin is facing up. There's nothing to win from dying at the proper time. I'm already exhausted from getting sad and getting happy.

So I'm sure I'll put a period on my life soon. Then the curtain will fall on the history of my life. It'll never be written to again. There could be no better time to quit while I'm ahead.

Sanagi remembered. The day they first met. The day he first let her touch him. The day they first kissed. The day he let her hug him.

Leaving Kousaka is my only regret. I really feel bad for him. What I'm about to do will mean betraying him. I couldn't ever apologize enough. I won't try to ask his forgiveness. If he hates me for it, I guess I'll just have to accept his anger. That's my natural reward.

...But if it's possible, I want Kousaka to think this.

The two of us should have been dead before we even met. Guided by our sick souls, we should have long since taken our lives. By the power of the worm, that was temporarily postponed, we were given a chance to fall in love, and one of us will even miraculously survive.

If he can take it like that, then while this may not be the ideal result, surely he won't think it's the worst.

If it weren't for the worm, we wouldn't have even met.

And it's not all sad. Because there's one fact that my death will prove. One fact that only my death could prove.

The death of the host is brought about by being released from the worm's influence. And the love between the two, formed by the Cupid-like assistance of the worms, should fall apart just by one of the hosts losing that influence. Thus, because I'm thinking about Kousaka just before I die, and Kousaka is thinking about me, that means our love could exist even taking the worms out of it.

We were able to love each other without depending on the worms.

That was something that could never have been proven if I hadn't lost them.

Sanagi let go of Kousaka's hand and gently stroked his cheek.

After a few seconds, he slowly opened his eyes.

"Sorry, did I wake you?"

"No," Kousaka shook his head. And then noticing something, his eyes widened. "...Sanagi, were you crying?"

She noticed it only after having it pointed out. She hurried to wipe it with her palm, but the tears kept pouring, showing no sign of stopping.

"That's weird." Choking up slightly, Sanagi forced herself to smile. "I didn't mean to cry..."

"Are you sad?"
"No, it's not that. In fact, I can't help but be happy."

"Huh. I'm relieved." Kousaka narrowed his eyes. "Those must be the right kind of tears, then."

He always he such a weird way of consolation, Sanagi thought and laughed.

"...Hey, Mr. Kousaka. Should I tell you something nice?"

"Nice?" Kousaka's eyes widened a little.

"Yes, nice," Sanagi nodded. Then she put on a special smile. "Um, I love you, Mr. Kousaka."

"Yeah. I know that."

"Not like that, I really do love you."

"Hmm." Kousaka thought about it, then sighed. "I don't really get it, but I'm happy."


The two laughed together. Before long, Kousaka should realize what I really meant by that, Sanagi thought. Though by then, it would all be too late.

Suddenly, she noticed her tears were making a stain on the pillow, and had a look like she'd done something wrong.

"Sorry. I'm going to make the pillow dirty at this rate."

Sanagi was about to get up, but Kousaka's arm blocked her.

"Well, we can just do this."

With that, Kousaka held Sanagi against his chest.

His shirt absorbed Sanagi's tears.

"You can cry as much as you want. I think you haven't cried for yourself enough before now."

"...Yeah. I'll do that."

Sanagi kept crying in his arms. For all that came before, and all that would follow.

Eventually, Sanagi stopped crying and fell asleep in Kousaka's arms.

It was an incredibly deep sleep.

It was the first time in her life she'd had such a peaceful sleep.

In her dream, she was a swan. A swan swimming lonesomely in a lake glittering in the sun during the spring. Her wing was injured, so she'd been left behind by the others. What am I going to do now? The swan couldn't bear the unease. She felt bitter toward the others who had left her behind, and at the same time thought nostalgically of them. And she cursed her lack of caution that caused her precious wings to be injured.

But as she swam in the lake upon which cherry petals fell, things gradually stopped mattering. Well, in the end, at least I'm able to have this beautiful sight all to myself, thought the swan.


Objectively speaking, even commonplace events can be world-changing incidents to the involved parties. For example, long ago, a woman told me this. The best memory of her life was in elementary school, when she was chosen to provide piano accompaniment for a chorus competition. When you've only heard that part, it might sound rather foolish. In fact, some people might think it's foolish even after listening to the whole story. It's all up to individuals to decide how they feel about things.

At the time, she was very reclusive and had no friends, and had no heavy burdens other than her role of providing accompaniment. Truthfully, she wanted to back out, but there was no one else in her class who could play piano, and she didn't have a personality that would let her refuse people's requests, so she ended up accepting. Days of being crushed by the worry of "what if I make a mistake during the show and drag everyone down?" went on, and she evidently cried to herself many times.

But once the chorus practice actually began, it soon caused her suffering no longer. In fact, she started looking forward to the practice sessions.

The conductor was a boy she secretly had affections for. When the performance began, he would always look directly at her. She knew, of course, that it was only eye contact for the sake of timing the performance. However, it made her happy. So much so that everything else stopped mattering.

Some people might laugh: "How lonely a life must that be if your greatest memory was just a boy you like looking at you?" But I understand her feelings very well. Even if the rest of her life afterward were filled with bliss, I believe her number one memory would remain "just a boy she liked looking at her."

People's standards of evaluation are rather haphazard. That full-course meal from an expensive restaurant you had when you were rich may not taste as good as a school lunch worth a couple hundred yen you had when impoverished, and you may not feel as much affection toward the girl who you spent most of your fulfilling college days with as you do the girl in middle school who held your hand once when you were down in the dumps. In terms of this book, I don't suppose Kousaka will ever forget the time Sanagi kissed him through a face mask. I suppose you could call it "happiness by subtraction." I consider this inversion of values to be one of humankind's most beautiful glitches.

If my previous books, The Place You Called From and The Place I Called From, were a story of physical defects, then Parasite in Love is a story of mental defects. In that sense, perhaps you could say the two stories have opposing structures. I had the idea of "the sickness of absence" in early spring 2014, but I had practically zero knowledge of parasites at the time. Miraculously, around that same time, the Japanese translation of Moises Velasquez-Manoff's An Epidemic of Absence was released by Bungeishunju, though I didn't learn of this until 2016. It was a deeply interesting book that I got very engrossed in, forgetting I was reading it for reference, so if reading this book gave you any interest in parasites, perhaps you might want to give it a try?

Also, the title of this book, Parasite in Love, was taken directly from Dr. Koichiro Fujita's book Parasite in Love (Kodansha). I'd like to deeply thank Dr. Fujita for generously allowing me to copy his title.

- Sugaru Miaki

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