Seventeen-year-old Jirou Azuma leads 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 battle arts. Jirou's life is thrown into turmoil after he rescues a seemingly ordinary black cat named Ragou, only to discover that the cat is actually a mononoke—a demonic spirit that has long been at war with humanity. When a hostile mononoke comes looking for Ragou, Jirou uses his shinobi training to defend the cat, but immediately suffers a mortal wound. Faced with the choice of devouring Jirou's fading energy to restore his own full power, Ragou instead chooses to give his remaining energy to Jirou. This transfer revives the boy and grants him great supernatural powers that complement his shinobi fighting style. This act is witnessed by Ryousuke Shiba, an officer in the Bureau of Espionage whose job involves dispatching aggressive mononoke. Shiba extends an offer to Jirou and his grandfather: to join the Bureau's new squad, Black Torch, and help them battle powerful mononoke who seek to devour innocent people.