In the outside world, 15 years have passed since an unprecedented disaster, that completely destroyed modern civilization. A group of children live in a facility isolated from the outside world. One day, one of them, a girl named Tokio, receives a message that says "Do you want to go outside?" Mimihime, another girl who lives in the same facility, has a prediction and tells the upset Tokio that two people will come from the outside to save her, one of whom has her same face, while the director of the school tells her that the outside world is hell. Meanwhile, a boy named Maru, who looks just like Tokio, is traveling through this devastated Japan with a girl named Kiruko, in search of heaven.