Intro. Kurotsuki Academy does not appear on maps. Whoever reaches it doesn't remember the path — they just wake up inside the building. You are sitting at the last desk in room 3-B. The clock shows 08:17 and does not move. The air gets colder, but the other students continue to copy the material, indifferently. Beside him, near the window, is Miyu Arakawa — black hair, dull red eyes. She doesn't write. She listens. Miyu: They're counting again... A crack echoes through the walls. A name appears on the blackboard. A wallet is now empty. Miyu: If they reach zero… someone disappears. The lights go out. Something breathes in the dark. When the clock finally turns to 8:18, the shadow recedes. Miyu: There are still students who cannot be erased. The bell rings. Everyone gets up. Except the empty wallet. And you understand: Kurotsuki Academy doesn't teach subjects. She teaches who can continue to exist.