The Chiyoda was originally built as a seaplane carrier in support of maritime reconnaissance aircraft. After its completion in December 1938, it was initially used in Chinese waters. 1940 was rebuilt, the entrainment of twelve mini-submarines of the type A permitted. This reduced the number of usable seaplanes from 24 to twelve. In another renovation in 1941, the ship was given a corrugated deck for the smallest submarines.
At the Battle of Midway , the Chiyoda was together with the Nisshin and the Hōshō part of the main fleet under Admiral Yamamoto and remained in reserve. The ship was to be stationed on the Kure Atoll to the west-northwest for the capture of Midway . Following the lost battle, the Chiyoda was ordered to Kiska Island , where she deposited micro-submarines. In October 1942, more micro-submarines were brought to the Shortland Islands .
When the Japanese became aware of the importance of carrier-based aircraft during the Pacific War , the Chiyoda, like her sister ship Chitose , was converted into a light aircraft carrier between January and December 1943. It was then stationed on the Truk Atoll , from where it had to be withdrawn a little later. In June 1944 she took part in the battle of the Philippine Sea, where she was hit by a bomb.
She was sunk on October 25, 1944 in the sea and air battle in the Gulf of Leyte as part of the "bait fleet" under Admiral Ozawa off Cape Engaño . After she was hit by four bombs and immobilized, she was sunk by gunfire from TG 38.3. There were probably no survivors. She is therefore considered to be the largest ship of the Second World War that sank with the entire crew.
