The previous successor to the Hokuto Shinken style. Ryuken (リュウケン, Ryūken?) was the sifu who adopted and trained Raoh, Toki, Jagi, and Kenshiro in the Hokuto Shinken style. After he chose Kenshiro as his successor, he was slain by Raoh, a feat made possible by chance; he suffered a stroke at the moment he was about to seal Raoh's fist. Kenshiro did not know the real cause of Ryuken's death, having been told that Ryuken died from illness, until Toki revealed the shameful secret during their first battle. Both Kenshiro and Raoh reflect on Ryuken's teachings during difficult situations. Ryuken appears in Fist of the Blue Sky under his former identity, Ramon Kasumi.

(Source: Wikipedia)