Other than being in a convoy 16-17 May, 1942 From Tokyo Bay to Yokosuka, and another convoy, West Convoy No. 61, that departed Tokyo Bay 8 December, 1942 bound for the Inland Sea, her record of movement are unknown until "Operation 81" begins.[2]
She left Rabaul, New Britain on 1 March 1943, as part of Operation 81, carrying troops, a cargo of equipment, fuel, 5 Daihatsu landing craft and ammunition for Lae, New Guinea. The convoy was attacked by aircraft of the United States Army Air Forces and Royal Australian Air Force from 2 March 1943, known as the Battle of the Bismarck Sea. Aiyo Maru was bombed on 3 March and sank at 07°15'S., 148°30'E. 45 crewmen and 278 soldiers were killed.[3] [4]