At the time of Japan’s surrender to Allied forces on August 15, 1945, some six million Japanese were left stranded across the vast expanse of a vanquished Asian empire. Half civilian and half military, they faced the prospect of returning somehow to a Japan that lay prostrate, its cities destroyed, after years of warfare and Allied bombing campaigns. Among them were more than 600,000 soldiers of Japan’s army in Manchuria, who had surrendered to the Red Army only to be transported to Soviet labor...