Keiji Yamaguchi (山口圭司 Yamaguchi Keiji, born February 17, 1974) is a former professional boxer from Hokkaido, Japan. Yamaguchi held the WBA light flyweight championship of the world, defeating Panamanian champion Carlos Murillo in 1996 via a 12th-round split decision.He is nicknamed "Prince" because his idol is Naseem Hamed, a superstar British boxer of Yemeni descent in featherweight class. So he imitated Hamed's fighting style, including trunk design as well.