In his last fight, he lost his crown and was defeated on a controversial split decision awarded to Japanese challenger Koichi Wajima in Japan.
He retired in 1973 after failing to come out for the bell in the 12th round against Koichi Wajima for the WBC and WBA light middleweight titles.
Koichi Ishii | Koichi Zenigata | Koichi Wakata | Koichi Wajima | Koichi Sakamoto | Koichi Nakamura | Koichi Domoto | ''Ruddock with Koichi Tohei Sensei in Iidabashi dojo (photo by Henry Kono)'' | Koichi Yamaguchi (bicycle framebuilder) | Koichi Yamaguchi | Koichi Tohei | Kōichi Tōchika | Koichi Tanaka | Kōichi Tabuchi | Koichi Sasada | Koichi Ohata | Koichi Nakano | Kōichi Morita (songwriter) | Kōichi Morita | Koichi Kato |