Inu-Oh's Father commands a prestigious Noh dance troupe during Japan's Muromachi period. Consumed by ambition for fame, he dons a demonic mask that compels him to murder biwa players. These killings inadvertently release the spirits of deceased Heike warriors. Seeking artistic renown, he forges a pact with the demonic mask, sacrificing his unborn son's innocence in exchange for achieving fame. This pact corrupts the unborn child, resulting in Inu-Oh's birth with severe deformities: multiple stubby limbs, an elongated arm, scaled skin, and a grotesquely disfigured face. The curse also inflicts significant physical trauma on Inu-Oh's mother during childbirth. He harbors profound contempt for his deformed son, forcing the boy into permanent mask-wearing to conceal his appearance and subjecting him to severe neglect. He confines Inu-Oh outdoors among dogs and feeds him dog food, explicitly denying him instruction in Noh dance despite being the troupe master. His abuse extends to his other sons, whom he verbally berates for failing to meet his exacting performance standards. When Inu-Oh gains popularity through revolutionary performances with the blind biwa player Tomona, the father succumbs to envy. He allies with the ruling shogun, Ashikaga Yoshimitsu, who aims to suppress Inu-Oh's subversive storytelling. Exploiting this alliance, he attempts to sabotage his son's performances to elevate his own status. His backstory is unveiled during a climactic performance by Inu-Oh and Tomona. The sequence reveals his demon mask pact, the murders of the biwa players, and the sacrificial corruption of his unborn son. Commanding the mask to kill Inu-Oh during this performance—a violation of their original pact—the mask instead turns on him. This results in his immediate, violent death through explosive disintegration.