Kiyosumi Katō, a martial artist and former top student of Doppo Orochi at Shinshinkai Karate, departed the dojo disillusioned by training methods he deemed ineffective for real combat. Seeking brutal, practical experience, he joined the yakuza. This period solidified his philosophy: martial arts serve solely as a tool for victory, directly opposing his master's ideals. Learning of the Underground Arena later drew him back to Japan, reigniting his desire to test his skills against powerful opponents. Standing approximately 180 cm (5'11") and weighing around 80 kg (176 lbs), Katō possesses a well-built fighter's physique. He has slicked-back black hair and dark eyes. Significant facial scarring marks him following his battle with Dorian. He typically wears tracksuits or sweatshirts but dons a traditional karate gi for arena matches. Known as the "Dangerous Lion of Shinshinkai," Katō employs an aggressive fighting style prioritizing ruthless efficiency and victory. He utilizes prohibited techniques like eye gouges and groin strikes. His technical arsenal includes Sokutou (side kicks to soft targets), Ippon Ken (extended knuckle strikes), axe kicks, soccer ball kicks, toe kicks, and Seiken (straight punches). Demonstrating tactical cunning, he once used improvised weaponry – rubber tubing and fishing line – to sever an opponent's ear, later attributing its possession to his fishing hobby. Katō exhibits pronounced arrogance and a volatile temper, especially when facing perceived disrespect or underestimation. He harbors deep frustration over his relative weakness compared to elite fighters like Baki Hanma or Yasha Ape Jr., whose superiority he struggles to accept. This insecurity fuels an intense drive to win, compelling him to employ underhanded tactics. Despite his rebellion and criticism of Doppo's methods, he maintains genuine respect and admiration for his former master, recalling frequent disciplinary actions without resentment. His combat capability places him below the series' top-tier fighters. He easily defeated mid-level opponents like fellow Shinshinkai students Takagi and Atsushi Suedō. However, he suffered significant setbacks against physically dominant adversaries, failing to injure Yasha Ape Jr. and being decisively defeated. Against death row convict Dorian Kaioh, he showed improved resilience and tactical ingenuity, inflicting minor damage despite the vast power disparity, but ultimately succumbed to Dorian's hypnosis. Katō's narrative arc frequently positions him as a supporting character who challenges protagonists but rarely secures decisive victories against major antagonists. Key moments include his humiliation and futile attack after Baki dismissed him as incapable of defeating Yasha Ape Jr., and his psychological vulnerability to Dorian's manipulation, where his desire for victory led him to hallucinate defeating an overwhelmingly superior opponent. His central conflict revolves around reconciling fierce pride in his karate skills with the recognition of his limitations within the series' fighter hierarchy.