Yō Kaiō holds the Chinese martial arts title of Kaiō, signifying mastery. He practices Chinese Kenpo with specialized Kongoken training, a regimen developing extreme strength and endurance. This forged his "diamond body," which endured impacts from wooden swords and chains, being run over by a heavily loaded truck, and a direct hit from an antique cannonball. He also remained conscious beneath a waterfall during a typhoon. However, this defense excels against fast strikes; its weakness is sustained crushing force. Biscuit Oliva exploited this by compressing his spine, nullifying his hardened physique. Personality-wise, Yō Kaiō is ruthless and arrogant. He relentlessly attacked Kaiō Dorian despite Dorian's apparent mental disability. Confident in his near-invulnerability, he openly challenged opponents like Oliva to strike him directly, believing no attack could harm him. His primary narrative role occurred during the Raitai Tournament, where he represented China. He faced Kaiō Dorian, overpowering him with techniques like an axe kick. Later, he fought Oliva, offering him a free strike to showcase his diamond body's resilience. Oliva's crushing grip destroyed his spinal column, ending his tournament participation.