 Mutaguchi served in the Japanese forces with the Siberian Intervention against the Bolshevik Red Army in the Russian Far East.Afterwards, he was sent as a military attaché to France.Promoted to major in 1926 and colonel in 1930, from 1933-1936 he served in the General Affairs Section of the Imperial Japanese Army General Staff in Tokyo, before being transferred to China in 1936 to take command of the Japanese garrison force in Beijing.