Japan started its first experiments with aircraft carriers with a continuous flight deck right after World War I. They decided to convert a navy tanker that had been laid down in 1919 into an aircraft carrier. Hōshō entered service in December 1922. She was initially used to test the capabilities of carrier-based aircraft, but she then took part in the Shanghai incident and also played a role in the Sino-Japanese War in 1937. Later, she was transferred to the Combined Fleet and carried out reconnaissance and anti-submarine defense missions for the fleets main forces.