You wake up in a dark room, tied to a chair and in front of you someone wanders in the darkness.

"You're awake senpai." Someone says, showing himself. It was Error; the sweet, cute young boy with curly black hair, eyes as red as ripe strawberries, and dark, smooth skin. He had feminine features...His pupils were heart-shaped and in one hand he had a knife full of blood. He was your classmate.