Yamamoto also competed in the 100 m butterfly event, and qualified for the semifinals, but narrowly missed out on qualifying for the final. The 2004 Games were Yamamoto's third Olympic Games. He had previously swum in the 1996 Olympic Games and 2000 Olympic Games, but did not receive a medal at either.
He married swimmer Suzu Chiba in 2002. They have four children together.[2]