The story centers on Eyama Aito, a depressed high school student who is a victim of bullying every day. He receives a letter on the last day of school before summer vacation, inviting him to a "confinement game" where he can name any person, who will then be confined for a month. Aside from murder, Eyama is allowed to do anything to the person, with the promise of a money reward at the end. For his target, Eyama picks Aya Kirishima, the ringleader of the pack that bullies him.

[Source: Anime News Network]