A high school sophomore named Akihito Kanbara is the protagonist of this grimdark fantasy. Although the little child has a human appearance, he is actually part Youmu and has the ability to quickly recover from any injuries he sustains. One day, Akihito runs across the first-year student Mirai Kuriyama just as it appears that she is ready to leap off the rooftop of the school. As a result of her power to manipulate blood, which is frowned upon by those who are a part of the spirit realm, Mirai lives a solitary existence. After Akihito successfully rescues Mirai, a series of unsettling occurrences start to take place.