 "Kasuga Maru" had been ordered by OSK and was fitting out when she was acquired by the IJN in 1940 and towed to Sasebo Naval Arsenal on 1 May 1941 to finish her conversion into an escort carrier.She was the first ship to be completed as her sister ships were not converted until 1942.The "Nitta Maru"-class ships were cargo liners that had a length of , a beam of and a depth of hold of .