In Tokyo, mutants have emerged who are thought to be connected to the divine. By consuming human blood, they reveal their true form, resembling the deity they are linked with. When Hachi's friend is attacked by one of these mutants, he resorts to drinking her blood in order to save her, utilizing his canine-like sense of smell. Volume 3 of the series features "Himitsu no Yami" as a prominent storyline.