From 1938–1940, "Taigei" performed normal operations in both northern and southern waters off Japan, with her primary mission being to support submarine operations off the coast of China from her home port of Kure in the Second Sino-Japanese War. She was reassigned from the 1st Fleet to the 6th Fleet on 15 November 1940 and was based at Kwajalein Atoll from 10 April 1941. Shortly before the start of hostilities in the Pacific War, "Taigei" was ordered back to Japan for conversion into a light aircraft carrier, arriving at Kure on 4 December.