After the collapse of the Tojo cabinet following the loss of Saipan, Ushiroku returned to Manchukuo to take command of the Japanese Third Area Army to oppose the Soviet invasion. Although his forces were composed mostly of undertrained or overaged reservists with obsolete weapons, he refused orders to retreat, and launched a counterattack along the Mukden-Port Arthur railway, buying time to allow many Japanese civilians to flee. By 13 August 1945, his formations were largely shattered, and a mutiny by the Manchukuo Imperial Army at Shinkyō ended his attempts to regroup. He surrendered to the Soviet army on 21 August 1945. He spent more than a decade as an internee in the Soviet Union. Ushiroku returned to Japan on 26 December 1956.