Jaku Kaiō is a Japanese martial artist holding the Kaiō title, an honor granted by the Chinese Martial Arts Association or an existing Kaiō for exceptional prowess. He serves as a martial arts instructor focused on training youth in Japan, motivated by recruiting strong individuals to join his school and mentor young fighters, often extending offers during combat. Physically, Jaku is medium-height with a stout build, a shaved head, and facial hair that shifts from an unkempt beard to mutton chops. He typically wears professional attire outside combat but shifts to a gi and black belt during fights, removing his glasses. His expertise centers on Kukendo, an eclectic Japanese style resembling mixed martial arts, integrating striking, grappling, and ground combat. He employs opportunistic and deceptive tactics, such as dislocating an opponent's arm during a feigned handshake or headbutting distracted adversaries. Key techniques include the Saninko Attsu pressure-point strike, precise backhand blows, headbutts, and submission holds. Jaku participates in the Chinese Challenge Tournament and Raitai Tournament as part of the Japanese-American Team. He confronts Kaiō Retsu, dislocating Retsu's arm during a deceptive handshake and later headbutting him mid-conversation. He also battles Kaiō Chin, employing a submission technique. Jaku demonstrates endurance by withstanding prolonged, full-force strikes from Retsu by strategically redirecting attacks to his back, which possesses higher damage resistance. Relationships include acknowledgment of Kaiō Kaku as his grandmaster and an acquaintance of Doppo Orochi. His appearance draws loose inspiration from Doshin So, founder of Shorinji Kempo, reflecting parallels in martial philosophy and technique.