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. He suffered a surprising defeat by "ippon" in a qualification match for the 1996 Summer Olympics, but was chosen as the representative anyway because of his past experience in the Olympic games. He ended his third appearance at the Olympics with a silver medal in the -78 kg division.