To save his mother, a kind-hearted boy and his tiny daemon friend set out on a journey across post-apocalyptic Japan as dark forces close in.

A nuclear explosion on Earth creates a rift that overlaps with hell, resulting in a devasting amount of dust pollution from Hell. Caught up in the chaos of the world is elementary school student Kento, who after finding a Daemon named Anna in the forest, decides to raise her. Together, the human and daemon pair embark on a journey to save Kento's mother.