In May 1934, when Kawamoto was a Waseda University student, he was selected the Japan national team for Far Eastern Championship Games in Manila. At this competition, on May 13, he debuted and scored a goal against Dutch East Indies. In 1936, he was selected Japan for 1936 Summer Olympics in Berlin and scored a goal against Sweden. 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.