Kenshi Yonezu/Hachi - IRIS OUT / JANE DOE

Natalie.mu, September 23rd, 2025 (Original Article)

Reze's Allure and Footprints Etched Into Two Songs, and Anecdotes of Creating with Hikaru Utada

Kenshi Yonezu releases his dual-A-side single "IRIS OUT / JANE DOE" on September 24th.

IRIS OUT was written as the theme song for the Chainsaw Man: Reze Arc movie, while JANE DOE is the ending theme for that same film. In JANE DOE, Hikaru Utada-san also took part in the vocals, performing a duet with Yonezu.

Chainsaw Man: Reze Arc is a theatrical adaptation depicting the story of the protagonist Denji, after suddenly meeting a girl named Reze, being toyed with by her while plunging toward an unforeseen fate. What concepts did Yonezu take from the work to create these two songs? In this interview with Natalie.mu commemorating the release, we spoke at length with Yonezu about the background behind the songs and anecdotes from his collaboration with Mys. Utada.

— Although the songs IRIS OUT and JANE DOE have entirely different flavors, I got the impression that they complemented one another. After you were contacted about Chainsaw Man: Reze Arc, where did you begin in making them?

First of all, it started with saying "we want two songs." It had been established that one song would be used for the ending, while the other they were considering playing at some point during the film. I had a firm idea from the start that I wanted to try something in particular for the ending theme JANE DOE, but for IRIS OUT, I remember having to find my way to what I should do.

— Were you progressing on both songs in parallel?

I started working on IRIS OUT first. Since it was decided it'd be a song played during the movie, I figured it would probably be best to get it done sooner in order to make production smoother as well. It was after finishing IRIS OUT that I then did JANE DOE.

— Regarding theme songs for Chainsaw Man, you previously made KICK BACK as well - were you thinking at all about connecting back to that?

From the beginning, I had a strong desire not to make it into any sort of "KICK BACK 2." I anticipated that JANE DOE wouldn't end up that way, but there was a risk of IRIS OUT becoming "KICK BACK 2" if I let my guard down the slightest bit. As such, I put considerable focus on how much I could distinguish it from KICK BACK. If KICK BACK, a dynamic song with a complex structure, was a roller coaster, I felt that IRIS OUT should be like a freefall - something pure and gallant that starts with a bang, heads in a straight line, and ends suddenly.

— My impression of IRIS OUT was that it's a song with a very narrow focus, in a good way. I thought it really expressed the hopelessness of Denji's character - what are your thoughts on that?

This movie, Chainsaw Man: Reze Arc, has Reze as a central character, so I thought it would be good to strictly focus on the relationship between Denji and Reze. Chainsaw Man, and Tatsuki Fujimoto-san's other manga, often feature women who whip men around. I think it's one of his characteristics as an writer, and it's a particularly major element here in Reze Arc. It was necessary to have that central axis of Reze, this extremely charming and alluring woman who has Denji at her mercy. I felt that if I powered forward with that as my focus, that would be a surefire way to set it apart from KICK BACK.

— In your comment from when the news first came out, you also stated that "I made this leaving open the pages with Reze on them 24/7 and staring at them." What about Reze do you think is captivating?

How she pleasingly pushes you around, and comfortably deceives you. Blushing and looking at Denji with upturned eyes, she may tease him a little, yet despite it all, she expresses "I have affection for you" too. I mean, of course a person like Denji gets deceived, and I think in a sense, wanting to be deceived is a rather important aspect of romantic feelings. She's charming and mischievous, but has mysterious aspects where you're not sure what she's really thinking. If you ask "just who is this girl?", it's like no one actually knows. She's this sort of figure who can throw your senses out of whack in an incomparably pleasing way.

— How did you develop that motif into the composition of IRIS OUT?

I wanted to make it an impulsive song. Slamming ahead in a straight line and ending in a flash. Including the way that I'm shouting out the lyrics, I sort of decided to make a song that's close to my image of punk. Though some people who listened to the song described it as "electroswing-like," which wasn't my intention at all.

— Is that so?

To the point that I only noticed once I was told that. I can't say I didn't feel a little bit of dissatisfaction, having people say it's "electroswing-like." Still, although I say I aimed in a punk-like direction, it's not like I wanted to necessarily do punk. If people hear the use of the piano and the swing-y feeling that way, I mean, it only figures they would. So it's sort of like "whoops, I guess it ended up electroswing-like."

— The voice samples used during the song, like Reze going "bon," are used very effectively. What were your thoughts behind including those, and the presentation?

It's actually an extremely simple story. At first, there weren't any voice clips there. As I was checking on previews for the film, I found they were way too well-done. I was even into the sound work - it really amplified my interest in the movie. For a preview, the level of polish was incredibly high. Since I felt so impressed with it, I asked "is it okay if I use this idea?", and put it in the song.

— How about the lyrics to IRIS OUT? What were you thinking about when choosing your words?

Regarding the lyrics, I had this worry that they might end up more violent, in a way, than KICK BACK's. The reason being, I had imagined before writing them that I'd be projecting feelings of sexual attraction onto another. By the nature of "singing" with your human voice as a method of expression, all kinds of sentiments can come out and be transmitted to the listener; compared to objective representations using a fictional world and fictional characters, such as manga and anime, singing can't avoid having a strong subjective quality to it. Part of me was thinking that if I wasn't careful, things could get pretty dicey. It feels like these days, it's becoming an era where sexual desires and emotions are avoided; I thought a lot about how I could find a compromise there, as a person who creates pop.

— And?

First off, I got the feeling that something which is adjacent to the avoidance of sexual desires and emotions is the practice of "stanning." So I got to thinking, what does it mean to "stan," anyway? These days, "stan" has become a handy word used for all sorts of things, so I'm going to limit myself to speaking about figures like idols who may well become the target of sexual feelings - but basically, I wonder if idols and the like aren't treated in a way akin to mythical and religious paintings from the Renaissance. This is strictly just my personal impression, though.

— Meaning, the targets of "stanning" are treated like religious figures?

Doing all sorts of training, polishing their dancing and singing and looks - in a way, they reign as god-like figures. So clean and graceful, the thought of even touching them is terrifying, yet at the same time I feel that they're people who have specialized for evoking sexual emotions. It depends on the stan whether they feel that way or not - of course, there are surely many who aren't looking at their faves in a sexual light - but they fundamentally possess both an aspect of mystery and an aspect of sexuality and humanity.

— And finding the beauty in that is something that Renaissance paintings have in common.

Renaissance paintings are a part of the Church's artistic endeavors, but at the same time, they have a kind of pornographic aspect as well, and that was made possible by their status as art. In recent years, it's become more common to say that outward expressions of sexual desire are morally wrong. When it's something one-sided that hurts other people, then I think that's fair to say. Thus, I feel like the word "stan" emerged as a deodorized form of those sexual emotions which can be seen as immoral and offensive. Compared to Renaissance paintings, which were an escape from having to be exceedingly pure, it's going along the opposite vector, but couldn't you say there's a similar duality there, right in the middle between modern idols and Renaissance paintings? "Stanning" has become a common activity these days, and many people find relief in it, so I don't want to come off like I'm rejecting it, but I think it's a word that was born out of normative awareness. I find that duality really interesting. Taking this into account, I thought what I could project onto IRIS OUT were sensations that waver in the space between morality and sexual emotions - a "moral ardent passion," a "moral romance."

— Let's hear about the ending theme JANE DOE as well. Based on the notion that it would play for the ending of Reze Arc, what sorts of ideas did you have at first?

First, I thought "I probably shouldn't be the one singing this." Being a man, my singing wouldn't really be appropriate for the ending of Reze Arc. I had the sense from the start that the song would predominantly need a feminine voice to work. In the film Dancer in the Dark, I really liked "I've Seen It All," where Björk and Thom Yorke do a duet. I felt like that sort of approach might fit really well here, so I started writing it with that in mind. It went through some twists and turns, and at one point I aimed for something in a nostalgic and youthful direction, but in the end, I thought a duet with a melancholic and dark atmosphere was most appropriate. That's how it went.

— In your comment for the announcement, you said that you "started without thinking too deeply about who I'd have sing it." At what point in making it did Utada-san come to mind?

I started by making the piano riffs, and around the time the melody and lyrics of the first verse were coming into view, I thought "it couldn't be anyone but Utada-san now." My personal impression of Utada-san's voice is that while it's melancholic and lonesome, it also has a huskiness, an eloquence that blows through you like the wind - it carries both those qualities. And also, listening to Utada-san's music, I feel as if it's almost dominated by their immense talent, the wonder of their composition and vocals. Like something from deep within them is permeating into me. But when I'm done listening, I also get an impression of them suddenly being gone, like "wait, where'd you go?" Possessing both that immense presence and that sparseness made them perfect for this song, I thought. Part of me even thinks it could never have worked without Utada-san.

— Hikaru Utada-san is an extremely versatile artist, so they've given form to all sorts of expressions in past songs. I think that in JANE DOE, Utada-san was able to draw out a particular sense of loss; what are your thoughts?

Two of my favorite songs of Utada-san's are FINAL DISTANCE and When Someone's Wish Comes True. Those two songs, which I heard in middle school, led to Hikaru Utada-san becoming a large presence in my life. The other day I went to a concert of theirs, where they performed a remixed version of the original DISTANCE. Compared to FINAL DISTANCE, they sang it cheerfully, with an overflowing feeling of euphoria. Even as they sang "we can't be as one," Utada-san danced so energetically. I really liked that. This is just my personal opinion, but that duality, that inability to pin down, that "not being what you expect," feels like a major part of their music. I wondered if there were some elements in common with Reze there. Not to say they're actually similar to Reze, of course.

— In IRIS OUT, you're singing lyrics from the perspective of Denji. Listening to JANE DOE with that in mind, one can make the assumption that you're having Hikaru Utada-san play the role of Reze. Were you thinking in that way?

I told Utada-san that I wanted to make a duet between a girl who's dealing with some incredibly complex things and a boy who in a fundamental sense doesn't understand that at all, and so requested they sing it as such. The form the song took is effectively the result of how they chose to interpret that. I didn't make any particular requests otherwise, basically just letting Utada-san do as they liked.

— What sort of communication did you have with Utada-san when recording and creating the song?

Utada-san lives in London, so our recording was done by sending data back and forth, like a correspondence. One time, we did speak on the phone, and they basically told me "I think if I sing like this, it'll make your voice seem more striking, Yonezu-san." And I was like, you're absolutely right. Indeed, Utada-san and I have completely different feels to our singing. Utada-san's a musician with roots in laid-back, highly rhythmic R&B and such. And my roots are more in Vocaloid and digital music, so part of me emphasizes the vertical grid lines. I also sometimes fall into alternative rock. Our natures are super different. So when you bring in Utada-san to a song I made, the vocals end up really well-rounded. I really like the disparity of it. Like I said before, it's a song based around the difference between a girl dealing with complex things and a boy who doesn't understand anything about that. That wasn't what I was aiming for whatsoever, so all I can say is that's what ended up happening, but it does feel like I ended up at a place where I'm like "maybe it could have only been this."

— What sort of concepts did you have in mind writing JANE DOE's lyrics?

The first thing I pictured was the imagery of standing barefoot on shattered glass, and walking over it while it injures you. Reze is a woman whose background is unclear, and a character for whom erasing traces of herself is a core part of her life. Someone with that sort of nature, walking on broken glass, injuring herself and bleeding, and thus leaving behind red footprints. That was the scene I imagined first. "So you were walking here, huh." I based my thoughts around how I could incorporate that into this song.

— The most striking part of the lyrics for me was the phrase "Let's fill up this world with mistakes" from the latter half. This part serves as the climax of the song, where both you and Utada-san's voices overlap. I found this verse very beautiful; what picture did you have of it?

While I think there's a side of it that's in line with the "moral sense" I talked about earlier, the stronger your desires and feelings of "I want it to be like this" get, the more they have to detach from that moral sense. It feels like there are spots where there's no avoiding being immoral. Everyone's writing the script to their own life and living it out, right? Perhaps the "better" way to live in this world is to unify that script with your morals. To let go of personal desires and live according to morality. That's a perfectly normal thing to do when living in society, and I have no intention of denying it, but when I think about working my personal desires and wants into that script, I have to separate from morality somewhere. When you write your own personal script and dance according to it, I believe that inherently means you'll bump your shoulder or arm into someone else. To the person you bumped into, it might seem beyond the pale, but when I bump into someone, or get bumped into myself, as much as possible, I want to think "you were just dancing to the script you wrote, weren't you?" Even if it was something immoral, or something seen as socially wrong, I want to maintain that feeling of "you were just dancing" to the very end. Of course, there are practical limits to these things; if you crash into someone badly, you aren't really in a position to say something so easygoing, so at those times you absolutely need morals and good sense, or laws and agreements - once again, I don't mean to negate such things. What I'm trying to get at here isn't about "affirming or not affirming mistakes," but the way in which you look at what's there. For instance, in Othello, normally the game starts with two white and two black pieces on the board, but suppose you had to play against someone as black on a board where all four starting pieces are white. Even if you object, they just insist "those are the rules." In that case, your only options are to obediently play a losing game where the white player crushes you, or abandon the rules and game entirely and flip the table over. That's just an example, but situations like that exist in reality. Looking toward positions like that is an important guide for me when creating music; at the very least, I want to value it as much as I can when making pop. I believe that's something partly made possible because it's pop. Those are the sorts of feelings I wanted to reside in these words.

— I felt this verse had a similar sense as Yukio Mishima's "The Temple of the Golden Pavilion." I think "beauty" contains quite a few of those aspects.

I like the word "odoriba" [can mean either "dance floor" or "landing" (as in on a flight of stairs)]. There are differing theories about the word's origin, but one of them is that when European ladies in the Middle Ages turned while climbing up stairs, it looked like they were dancing, so they came to be called odoriba ["the spot where you dance"]. But a landing is just an empty place on a stairwell, right? I really like the mental image of "dancing in an empty place," so occasionally I'll use the word "odoriba" in lyrics. Maybe that's a result of me feeling like it might be better to pay no mind to things being "unproductive," or perhaps, like I said earlier, "immoral."

— Let me also ask about the single's artwork, packaging, and music videos. What sorts of things did you focus on when drawing Reze for the cover illustration?

I decided I'd draw her as seductively as my skill would allow. It felt like it wouldn't be suitable at all without that impression she was alluring you. Drawing her that way to the best of my ability, that's how it ended up.

— How about the contrast between the IRIS OUT and JANE DOE covers? I felt the feet drawn for JANE DOE have a connection to the lyrics.

When I realized I'd have to draw two covers, I decided to draw Reze's entire body, then divide it into her upper and lower halves.

— The IRIS OUT Disk comes with a Polaroid, an acrylic stand, and a pouch case; the contents of the package seem connected to what we discussed in this interview as well.

That's true. Once I decided I would draw Reze's full body, I figured it should include an acrylic stand. I had been thinking "what's "stanning" all about?" and all too, so almost as a parody of idols, I thought it'd be good to make that manifest.

— What were you thinking about regarding for the music videos?

For IRIS OUT, like I said before, the previews were really good, so I had the people who made those create it using footage from the movie itself. For the JANE DOE video, I shot it with Utada-san. The director was Tomokazu Yamada-san. He's filmed lots of Utada-san's music videos lately, and he's filmed Kenshi Yonezu music videos for a long time too. I felt he was the only possible choice for director.

— How was it filming with Utada-san?

It hardly felt real. Sitting back to back with Utada-san, we spent much of the recording just spinning around and letting the camera film it. That aspect included, it felt kind of like a dream. It was my second time meeting Utada-san, and they were as sociable, frank, and easy to speak with as ever. A wonderful person, no different from how they appeared on the other side of the screen.

— Having connections as creators, such as via Director Yamada and engineer Masahito Komori-san, I always felt it was inevitable you two would do something together somehow, but it's deeply moving to think that this was the time for that to happen.

If you made a chart of connections based around myself and Utada-san, there'd be a surprising number of people we have in common. But indeed, if it weren't for the wonderful original work of Chainsaw Man, I don't think I'd have ever considered calling on someone like Utada-san for one of my songs. I feel very grateful to Chainsaw Man that it created these sorts of opportunities for me.

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