Takuo Mitsui grew up in the Hakata Bay of Fukuoka city and was an alumnus of the medical faculty of Kyushu University at the time of the 1936 Berlin Olympics. He originally teamed up with Kazuhiko Tatsuno, a law student also from Kyushu University. But since Tatsuno was unable to attend, Minoru Takarabe took his place in the Star class at the Berlin Olympics. One year later the club of Kyushu University, initially a rowing club, was renamed as Kyushu University Yacht Club. At the 1964 Tokyo Olympics, Mitsui served as an officer. In 1946, he published his thesis on “The effects of carotid endarterectomy on central retinal artery blood pressure and electrocardiography”.