In December 1937, Kofukuda was promoted to full Lieutenant and assigned to the carrier "Ryūjō" as its fighter squadron leader ("Buntaichō"). In June 1938, he was posted to the 12th Air Group in Central China, which operated from Nanjing at that time, but then gradually moved to Anqing, Jiujiang and finally to Hankou with the Japanese advance up the Yangtze river. He returned to Japan in December 1938 and was assigned to Ōita Air Group. In November 1939, Lieutenant Kofukuda was transferred to 14th Air Group, which moved to Hanoi, Indochina in Autumn 1940. On 7 October, he led six new Mitsubishi A6M Zero fighters to escort a strike of 27 Mitsubishi G3M bombers against Kunming. In the ensuing air battle with Chinese fighters, they claimed 13 enemy aircraft destroyed.