Kaioh is the primary antagonist of the Shura arc of the Fist of the North Star storyline. As the most powerful of Shura's three generals and a master of Hokuto Shinken's sister art, Hokuto Ryuuken, he has given his heart and soul to darkness in exchange for incredible spiritual power. In his first battle with Kenshiro, he easily defeats the Hokuto Shinken master and leaves him severely battered. However, Kenshiro lives, and having seen the power of Hokuto Ryuuken, is able to defeat Kaioh in their rematch.
Kaioh is the long-lost brother of Raoh, one of Kenshiro's adopted brothers and fellow students of Hokuto Shinken. It had been Raoh's intention to return to Shura and stop his brother once he had established his empire and defeated Kenshiro, but such was not to be. Kaioh was also responsible for sealing away the memories of Kenshiro's brother Hyou and manipulating his emotions to turn him into Kenshiro's mortal enemy. To do so, Kaioh went so far as to murder his own sister Sayaka, with whom Hyou shared a romantic relationship.