Black Oni reigns as the central antagonist, a formidable demon whose dominance over the Red Oni enforces ruthless servitude through fear. He rules a mountain domain, unleashing terror upon neighboring villages by demanding recurring sacrifices of young women to satiate his hunger. This tyranny culminates in the abduction of Aya, a pivotal act that compels the protagonist to challenge him. After the Red Oni’s initial downfall, Black Oni seizes Aya, intensifying the confrontation. The protagonist faces him in a climactic clash, emerging triumphant to dismantle his oppressive reign, free the captive villages, and secure Aya’s release. Black Oni’s manipulation of the Red Oni underscores the harsh hierarchy dictating supernatural power dynamics. His defeat catalyzes the Red Oni’s transformation from a tormented servant to a willing ally, later supporting the protagonist against looming threats.