A renegade of the Hokumon temple, who has a love-hate relationship with his father Sanga. He took over Lastland while Kenshiro visited the Hokumon temple retrieving medicine for Bista. It was revealed that Seiji learned all the secrets of Hokumon no Ken in less than three years. After losing to Kenshiro, he committed suicide by pressing the fatal point Heiketsushu (閉血愁) in his body to atone for his past crimes.
