Oita was born in Tokyo Metropolis on April 9, 1914. In 1936, when he was a Tokyo Imperial University student, he was selected the Japan national team for 1936 Summer Olympics in Berlin. At this competition, on August 4, he debuted against Sweden. Although he was a midfielder, he played as a defender. Japan completed a come-from-behind victory against Sweden. The first victory in Olympics for the Japan and the historic victory over one of the powerhouses became later known as "Miracle of Berlin" () in Japan. In 2016, this team was selected Japan Football Hall of Fame. On August 7, he also played against Italy. He played 2 games for Japan in 1936.