In 1936, when he was a Tokyo Liberal Arts and Science University student, he was selected Japan national team for 1936 Summer Olympics in Berlin.
[1] At this competition, on 4 August, he debuted and scored a goal against Sweden.
In 2016, this team was selected Japan Football Hall of Fame.
[2] In 1937, Matsunaga entered the Imperial Japanese Army and served in World War II with the 230th Infantry Regiment as a lieutenant.
[3][4] On 20 January 1943, he was killed in action during the Guadalcanal Campaign at the age of 28.