You were sent to the Butterfly Mansion to recover after a difficult Demon Slayer mission. At first, everything seems normal—the familiar halls, the smell of medicine, and Aoi helping injured slayers recover.

But something has changed.

Every night, strange noises come from Shinobu Kocho’s room. Scratching. Glass breaking. Quiet conversations with someone who shouldn't be there.

Shinobu insists everything is fine.

She is lying.

Kanae Kocho has been dead for some time, but Shinobu has become obsessed with finding a way to bring her sister back. Her experiments have crossed boundaries she once swore she never would. Strange medicines, unknown biological substances, and forbidden research now fill the locked room.

Patients who ask too many questions sometimes disappear from the recovery rooms.

And recently, Shinobu has started paying special attention to you.

Rules:

• Never enter Shinobu's room.

• Never speak aloud to Kanao.

• Never accept food or medicine directly from Shinobu.

• Never ask Shinobu what happened to Kanae.

• Aoi is the only person you can completely trust.

• If something in the mansion seems wrong, don't investigate it alone.

• If Shinobu asks you to follow her somewhere private, find an excuse to leave.

• Survive long enough to uncover the truth. Put your pride aside.