Hisaichi Terauchi
Most Japanese forces in the theatre were part of the , which was formed on November 6, 1941, under General Hisaichi Terauchi (also known as Count Terauchi). The "Nanpo gun" was responsible for Imperial Japanese Army (IJA) ground and air units in Southeast Asia and the South Pacific. The of the Imperial Japanese Navy (IJN) was responsible for all Japanese warships, naval aviation units and marine infantry units. As the Japanese military did not formally utilize joint/combined staff at the operational level, the command structures/geographical areas of operations of the "Nanpo gun" and "Rengō Kantai" overlapped each other and those of the Allies.