日本体育大学
Aihara took up gymnastic at the age of 15 while studying at the Nippon Sport Science University. He was coached by his future teammate Masao Takemoto. In 1964 he married Toshiko Shirasu-Aihara, a fellow gymnast. Because of an injury he missed the Tokyo Olympics that year, and soon retired to become a gymnastics coach. In 1979 he founded the Aihara Gymnastics Club.