Mamoru Yamaguchi (born May 29, 1977) is a Japanese mixed martial artist who competes in Pancrase. He is the former Shooto Bantamweight (123 lb) Champion, former Shooto Featherweight (132 lb) Champion, former Pancrase Flyweight Champion, as well as a former King of the Cage Junior Flyweight Champion. Mamoru is known for his counter striking and his trilogy with the former Shooto Bantamweight Champion Shinichi Kojima. His afro is a tribute to Japanese boxing legend, Yoko Gushiken.