Ushio to Tora (1992)

The story of Ushio Aotsuki, who is always being pursued and helped by a huge, uncanny, and occasionally invisible tiger-like monster named Tora, is the focus of Ushio & Tora. Ushio's family runs a temple in Japan where, 500 years ago, a samurai ancestor of theirs fought the same monster to a standstill and, after using a cursed spear known as the "Beast Spear"—which bestows strength, speed, and endurance upon its wielder in exchange for his soul—trapped him against a rock. Tora was stuck within their cellar door when Ushio unintentionally unlocked it.