On 8 December 1941, the 5th Division landed in Singora, Thailand, and moved south to break the British defense line at Jitra in northern Malaya. A detachment was organized around Saeki's 5th Scout Regiment. With 580 infantrymen, 18 tanks and armored vehicles, and two artillery pieces, Saeki conducted a mini-blitzkrieg on British defenses at Jitra, which was held by 6,000 defenders. This successful attack led to the total collapse of the British defenses in northern Malaya.
Promoted to colonel, in July 1944 Saeki took command of the 29th Tank Regiment. In April 1945, he received command of the 2nd Independent Tank Brigade organized for the defense of the Japanese home islands. Saeki died in Tokyo on 15 May 1980.
Allen, Louis. Singapore, 1941–1942. London: Davis-Poynter, 1977. Reprint, London: Frank Cass, 1993.