Kaioh stands as the eldest brother among Raoh, Toki, and Sayaka in the Ryou family, historically servants to the Hokuto Soke Clan at Taiseiden. He watched helplessly as his mother sacrificed herself in a Taiseiden fire to save infant members of the Hokuto Soke line, including Kenshiro. This trauma, compounded by later humiliations, ignited a deep-seated resentment towards the Hokuto main lineage. Rejecting love and empathy to bury his grief, Kaioh initiated his descent into evil by killing his loyal pet dog, symbolically severing his humanity. Forced into servitude under Jukei in the Land of Shura, Kaioh mastered martial arts but was repeatedly compelled to lose sparring matches against Hyoh to bolster Hyoh's confidence. Jukei enforced this manipulation by threatening Kaioh's siblings. After one such defeat, Kaioh retaliated by brainwashing Hyoh using Hokuto Ryuken techniques, erasing Hyoh's memories of Kenshiro and implanting false familial bonds. Kaioh subsequently conquered Shura alongside Hyoh and Han, declaring himself the First Rashō (supreme leader) of Asura. He ruled through terror, determined to eradicate Hokuto Shinken and usher in an era dominated by Hokuto Ryuken's dark principles. Kaioh orchestrated elaborate schemes against Hokuto Shinken. He kidnapped Lin to exploit her Celestial Emperor bloodline, intending to father children who could purify his family's perceived "curse." He tortured Kenshiro and crucified him under the Big Dipper for public execution, though Kenshiro escaped with allies. To force a final conflict between Kenshiro and Hyoh, Kaioh murdered his sister Sayaka and framed Kenshiro for her death. Demonstrating his contempt for love, he struck Lin's Shikanhaku pressure point, ensuring she would fall in love with the first person she saw upon waking. Kaioh embraced absolute evil, viewing love and compassion as fatal weaknesses to be purged. He covered his body with self-inflicted scars as a physical manifestation of his rejection of empathy. Yet, he maintained a meticulously kept tomb for his mother, revealing residual reverence for her memory. His defeat by Kenshiro at Lake Masho exposed his internal conflict; he initially pleaded for strength from his mother for a final attack but ultimately accepted his loss. When the dying Hyoh offered forgiveness instead of revenge, Kaioh expressed remorse, wishing for rebirth alongside Hyoh and Sayaka as ordinary children. He carried Hyoh's body into a lava flow, fossilizing with him into a statue. As the supreme master of Hokuto Ryuken, Kaioh wielded Matōki (Demonic Aura), a visible manifestation of his evil energy. This aura enabled projectile attacks, defensive shields, area-of-effect blasts, and techniques like Anryu Tenha to levitate opponents. His armor restrained the aura's corrosive effects. Key techniques included Anryu Hiha (long-range energy blasts), Seimyo Danretsu (rapid strikes), and Kento Shadan (defense-shattering palm strikes). His mastery allowed him to temporarily disrupt Kenshiro's Musou Tensei. In spin-off media, his combat style emphasized concentrated dark energy attacks, such as Demonic Ground Shattering Wave and Incineration of Ignorance, often depicted with explosive visual effects.