Kazuo Onoda graduated from Meiji University and was among the first generation of successful Japanese inter-war swimmers. He was initially selected for the Antwerpen Olympics, but eventually did not take part. At the Paris Olympics he acted as captain of the Japanese swimming team and narrowly missed a medal in the men’s 4 x 200 m freestyle relay. In 1923, he represented Japan at the 6th Far Eastern Games and won the freestyle event over 50 y and the freestyle relays over 4 x 50 y, 4 x 50 m and 4 x 200 m. Additionally, he was second in the freestyle events of 100 y, 440 y, 50 m and 100 m. Nationally, he won three titles at National Swimming Tournaments in 1920, four in 1921, and one in 1923.