sentences:  Koga returned to the Olympics in 1992 after winning the 1989 and 1991 World Judo Championships, but seriously injured his left knee during a randori (sparring) session against Hidehiko Yoshida, which prevented him from using his best technique; the Ippon Seoinage.He won the gold medal overcoming this injury, and was given the JOC Sports Award by the Japanese Olympic Committee.Koga briefly retired from competitive judo after his victory at the Olympics, but made his return with a gold medal at the 1995 World Judo Championships in Chiba, Japan.