Shizuo was born on 25 October 1913 in Yokohama, Tokyo Prefecture, and studied shipbuilding in the Department of Marine Engineering at the Imperial University of Tokyo, graduating in 1938. From August 1941 he served on the staff of the Naval Technical Research Institute (海軍 技術 研究所). He was then sent to Singapore working at 第101 工作 部 (101st Design Division) at Seletar Naval Base, repairing ships and sweeping mines, most notably overseeing the repair of the destroyer Amatsukaze which had lost its bridge and front two boiler rooms by a torpedo.