Shunsei Kaku, the 26-year-old son of prominent Chinese martial artist Kaioh Kaku, was conceived when his father was 120 years old. Known as "Shunsei the Crazy Beast" and "Invincible Beast," he exhibits a cold-blooded and arrogant personality mirroring his father's. At the Raitai Tournament, following the Chinese team's first loss, he interrupted his father's strategy meeting to demand each team member kill one opponent, asserting eliminating all five would erase the defeat. He declared victory the moment his father agreed, supremely confident in his superiority over non-Chinese fighters. Outwardly close to his father, their relationship held emotional distance. Shunsei entered the Raitai solely at Kaioh Kaku's request. However, after Baki Hanma knocked him unconscious with a single punch to the jaw in under two seconds, Kaioh Kaku disowned him, declaring his true son would never lose and commanding him to abandon martial arts, revealing the bond's conditional nature. Physically, Shunsei is tall and muscular with black hair and a heart-shaped face. His eyebrows possess a sharp downward slant, creating a sinister expression often paired with a peculiar smile. He typically wears a jacket and pants featuring intricate tree patterns. Trained in Chinese Kenpo, his precise martial abilities remain undefined due to his brief appearance. He demonstrated notable speed, yet insufficient against Baki Hanma. His "Invincible Beast" moniker implies past dominance, but his catastrophic defeat exposed critical vulnerabilities: his neck lacked the durability to withstand high-caliber strikes, and he habitually underestimated formidable opponents. This overconfidence, combined with his father's repudiation, concluded his known arc. A misconception suggesting he is 120 years old stems from his father's age at conception; Kaioh Kaku was 146 during these events, confirming Shunsei's age as 26.