Hokuto Shinken
is a former rival of Ryuken who competed against him for the succession of the Hokuto Shinken. During the duel, both Koryu and Ryuken realize that their strength and skills are equal, and that both of them could be killed in the fight. Acknowledging that, Koryu decided to give up the successorship to Ryuken, and to begin living an ascetic peaceful life in the mountains. Raoh, after healing himself of the wound given to him by Kenshiro, challenges Koryu to test his body and defeats him. Raoh, however, spares the lives of Koryu's two sons, Zeus and Aus.