 As a vice admiral from 15 October 1940, Komatsu commanded the Ryojun Guard District in 1941, and was commander in chief of the 1st China Expeditionary Fleet from 5 July 1941.After the outbreak of the Pacific War, he was reassigned as commander in chief of the 6th Fleet, effectively controlling Japanese submarine operations, from 16 March 1942 to 21 June 1943.From June 1943 to November 1944, he was commander of the Sasebo Naval District.