Like many other children, Ryou Tanabe wants to grow up to be a resolute hero. However, for reasons unknown to him, he can see and interact with spirits, the unusual ability sometimes leading to situations out of his control. During a middle school field trip, a fox spirit possesses and prompts Ryou to attack his classmate. As a result of his unconscious actions, Ryou is bullied by his fellow students and becomes an outcast, shutting him out from achieving his true childhood ambition.

One day, Ryou wakes up to an anonymous mail that signals for help. Finally given a chance to redeem himself, an ecstatic feeling overwhelms Ryou as he mentally resolves to realize his dream. He steps outside his room, only to be devastated to discover that the normal world he once knew has been transformed into an apocalyptic wasteland. While looking for survivors, he comes across a dead body with its soul lurking nearby—his little sister Yuka Nishizono. Despite the pair having a complicated relationship, the two work together to uncover the reason behind the sudden alteration of their society into a dystopia that reeks of ruin.