Seventeen-year-old Jirou Azuma lives a quiet life with his grandfather, using his supernatural ability to communicate with animals to befriend and protect them. Both Jirou and his grandfather are descendants of a long-standing shinobi clan, training in combat to preserve their family's martial arts. Jirou's life changes dramatically after he rescues a seemingly ordinary black cat, Ragou, only to learn that the cat is actually a mononoke—a demonic spirit at war with humanity. When a hostile mononoke comes after Ragou, Jirou uses his shinobi training to defend the cat but suffers a fatal injury. Faced with the choice to consume Jirou's dwindling energy to regain his full power, Ragou instead decides to transfer his remaining energy to Jirou. This revives the boy and grants him powerful supernatural abilities that enhance his shinobi fighting style. This event is witnessed by Ryousuke Shiba, an officer in the Bureau of Espionage, whose role involves dealing with aggressive mononoke. Shiba offers Jirou and his grandfather a chance to join the Bureau's new team, Black Torch, to help combat powerful mononoke that threaten innocent lives.