WBC Featherweight Champion from January-July 2006, became the oldest Japanese boxer to win a world title at 35 years old.
He played baseball as a teenager but took up boxing after his father founded a boxing gym.
He took over for his father at the head of the Fukuoka Boxing Gym after retirement from fighting.
His father, Hidetake Koshimoto, was previously head of the Fukuoka Boxing Gym.
He and Mexican fighter Salvador Sanchez have both been WBC Featherweight champions.