Ryuho began as the submarine tender Taigei, launched on 16 November 1933 and commissioned on 31 March 1934. She was ordered back to Kure shortly before the Pacific War for conversion to a light carrier. The conversion at Yokosuka took far longer than planned and was not finished until 30 November 1942; as Taigei she was the only major warship damaged in the Doolittle Raid. She was one of the least successful of the light carrier conversions because of her small size, slow speed and weak construction, and she was used mainly for ferrying aircraft and training.
On 12 December 1942, on her first ferry mission to Truk, the submarine Drum hit her with a torpedo near Hachijojima, and she went back to Yokosuka for repairs. In June 1944 she sailed with the Combined Fleet as part of Force B, with Hiyo, Junyo, Nagato and Mogami, in the Battle of the Philippine Sea. After a ferry run to Formosa she left for Japan on 2 January 1945 escorted by Isokaze and reached Kure on 18 January, the last Japanese carrier to venture outside home waters. She was struck from the navy list on 30 November 1945 and scrapped in 1946.
Sources: Wikipedia (ship articles), the Kure Maritime History Science Museum photograph records on Wikimedia Commons, and combinedfleet.com for the Chitose-class histories. No commanding-officer records were available for these ships.