In August 1940, he was promoted to lieutenant general and given command of the IJA 21st Division. As part of the Japanese 12th Army, the division participated in counter-insurgency operations in northern China as well as the Battle of South Shanxi in May 1941, and the subsequent Hundred Regiments Offensive. From November 1941, the division was transferred to the control of the Southern Expeditionary Army Group and transferred to the Philippines, landing at Lingayen Gulf in February 1942 for the Philippines Campaign. Tanaka was transferred to command the IJA Twenty-Third Army in China from March 1943. This was primarily a garrison force to deter the possible landings of Allied forces in southern China. It was involved in the Battle of Guilin-Liuzhou (part of Operation Ichi-Go) from August to November 1944 and surrendered to the Chinese Kuomintang forces on August 15, 1945 with the surrender of Japan.