Upon waking up, Yuuki Oku has no recollection of his past and finds himself being chauffeured to a secluded school. Upon arrival, he is ushered into a classroom where only six other individuals are present. He is appalled to discover that each person, including himself, is a delinquent lacking a crucial component, such as an appendage, an organ, or, in Yuuki's case, memories. As pupils of the class, they are all incomplete. They are also informed that one of them is an artificial being created from the personages' stolen body parts.
In order to escape, Yuuki must complete his education within a week. But even if he attains graduation, he must still identify the puppet among his classmates and reclaim what was taken from him.