Retsu is a Chinese martial artist and a kenpo master, being one of the expert martial artist who held the prestigious title of Kaioh (lit. "Sea King") for his prowress. While he is proud of "4,000 years of Chinese martial arts" history and is eager to prove its prowress to the world though underground fighting tournament, he also recognise other strong-willed fighters and often befriending them.
He is later killed by Miyamoto Musashi in battle, and his severed right arm was later grafted onto Orochi Katsumi as a replacement for his own right arm that were lost during his fight with Pickle.
