While cleaning his family's Buddhist temple, middle-schooler Ushio Aotsuki uncovers a cellar where a tiger-like yokai has been pinned for five hundred years by an ancestor's weapon, the Beast Spear. The sealed creature draws other monsters to the temple, and Ushio is forced to release it to survive, naming it Tora. Bound by the Spear and stalled from devouring the boy, Tora becomes a grudging ally as Ushio confronts the supernatural threats the weapon attracts.