A delinquent kid who talks to animals gets fused with a cat and suddenly understands he's been drafted into a war nobody told him about. The show knows the real power isn't the transformation or the mononoke fights, it's that Jiro actually cares what happens to the creatures caught in the middle. Every supernatural battle becomes personal because he refuses to treat anything as just another monster to kill.

Seventeen-year-old Jirou Azuma comes from an old shinobi clan and lives with his grandfather, who trains him in the family's combat arts. Jirou can also speak with animals, and he uses that gift to befriend and protect them. After he helps an injured black cat named Ragou, he learns the cat is a mononoke, a demonic spirit, and in fact the legendary Black Star of Doom. When a hostile mononoke hunts Ragou down, Jirou is gravely wounded defending him. Ragou gives the boy his remaining energy, reviving him and granting him supernatural powers. Ryousuke Shiba of the Bureau of Espionage sees this happen and invites Jirou and his grandfather to join a new squad, Black Torch, to fight dangerous mononoke.