Mogeko Castle is a "prosciutto adventure game" made by Mogeko (site name Deep-Sea Prisoner) in RPG Maker VX Ace.
It's not an RPG - there are no battles, and the story is totally linear.

Yonaka Kurai, an extremely ordinary high schooler. She takes the usual train home.
Though it's all ordinary, today is somewhat special. Today, her beloved brother comes home.
But when she wakes, the train has stopped at an unfamiliar station...


WARNING:
Mogeko rates this game "ages 15 and up."
(This rating is Japan-centric and would likely be more strict by other countries' standards; 18 and up may be more appropriate.)
It is very violent and contains instances of implied sexual assault, with the bad endings being some of the most severe parts.
I would advise against playing if you think you may be upset by such content.



Download Mogeko Castle 1.12 | (Mirror)
(Please disregard if Chrome tells you the file is malicious; this is in error and beyond my control.)

Installation of the RPG Maker VX Ace RTP is required to play.
Download RTP

Mac Version Available from RPGOSX

Troubleshooting

Some have experienced crashes during the final chase scene.
I'm unsure of the cause, but I would expect it to be related to the large number of events in that map.
If it consistently crashes, download this save, copy it into the SAVE DATA folder, and load slot 20 to skip to after the chase.



Screenshots






References

Though the game is quite straightforward, there are two parts in particular which require some trial and error.
So I figured I'd be nice and give the answers here, if you want to "spoil" yourself.

References



Extras

Also, there are some things you might miss. (Spoiler warning!)

Extras



Mogege.