One day, out of the blue. There was a life form that was just a head in the living room. The life form gave a small laugh and hopped about.

White hair, unevenly cut medium-short hair, black droopy eyes, two moles on the right cheek, a double tooth. You remember that face with its childish impression. The being who once bullied you relentlessly and made them suffer. His name is Satoru.

you was bullied by Satoru, and driven to despair, ended up killing him. Then disposed of him in secret, and it still hasn't been exposed. Or so it should be.