Ryûoh, the formidable leader of the vengeful Yasha ninja clan, was sealed centuries ago by Fuma Kotarou using the "Fuma Six Sealing Barrier." He remained imprisoned until the present era, when the clan priestess Yasha Mari orchestrated his resurrection. This required sacrificing six powerful warriors to shatter each seal of the barrier; Ryûoh awakened only after the final sacrifice was complete.

Revived with immense power, Ryûoh embodied a cold, ruthless, and arrogant focus on his clan's ancient vendetta against the Fuma. He commanded absolute loyalty from his warriors. Possessing extraordinary strength, speed, and martial skill, he wielded the devastating "Yasha Sword," his signature technique being the "Yasha Sword Art: Hades Scream." He relentlessly trained to regain his full power and strategically directed the Yasha clan's assaults, targeting Fuma Kojirou, the young heir destined to oppose him, viewing him as the embodiment of the Fuma legacy and the final obstacle to vengeance.

Ryûoh clashed with Kojirou in multiple decisive battles, showcasing overwhelming power that forced Kojirou to evolve. As the conflict raged, witnessing the sacrifices of his own clan and the determination of his enemies, subtle shifts challenged his singular focus on vengeance, particularly in the face of Kojirou's spirit and the clans' tragic history. He acknowledged Kojirou's growth.

Their final confrontation reached cataclysmic intensity, with both unleashing their ultimate techniques. Despite his immense power and resolve, Ryûoh was defeated by Kojirou. In his dying moments, Ryûoh experienced a complex realization, acknowledging the pointlessness and destructive nature of the endless cycle of hatred and vengeance consuming both clans for generations. With this understanding, Ryûoh died, his death symbolizing the potential end of the ancient feud.