Ramon Kasumi, later called Ryūken, was the younger half-brother of Kenshiro Kasumi, sharing their father Tesshin Kasumi but born to different mothers. His early years defined him as a martial guardian, shielding Aya Kitaōji from mercenaries and safeguarding Pan Yuling against the Tàihú Bāng during her time in Japan, cementing his reputation within the Hokuto Shinken tradition.

Present at his adoptive nephew Kenshiro’s birth in 197X, he bestowed the child’s name in honor of his brother, recognizing their identical Big Dipper birthmark—a symbol binding Hokuto Shinken’s legacy. His youth culminated in a fierce succession duel against Kōryū, securing his role as the 63rd heir of the lineage.

As mentor to Raoh, Toki, Jagi, and Kenshiro, he molded them into formidable fighters. Choosing Kenshiro as successor ignited tensions with Raoh, who seized a moment of vulnerability during Ryūken’s heart attack to strike him down while he tried to suppress Raoh’s defiance. The truth of his death stayed hidden until Toki disclosed it during Kenshiro’s climactic clash with Raoh.

His legacy intertwines with familial and historical currents, including his brother Kenshiro Kasumi’s abrupt exit to Shanghai, which thrust Ramon into interim leadership. His teachings and choices shaped the Hokuto Shinken school’s fate, bridging the eras chronicled in *Souten no Ken* and *Fist of the North Star*, while underscoring the cyclical struggles of succession and the weight of tradition.