This class consists of TATEYAMA and OYAMA MARUs, respectively completed in 1937 and 1941 for various shipping companies. OYAMA MARU was requisitioned by the IJA and served as Army transport No. 458. She was torpedoed and sunk by an American submarine in Apr ’43. TATEYAMA MARU was requisitioned by the IJN and registered in Sep ’41 as an auxiliary water tanker. She was bombed and sunk by carrier-based aircraft in Dec ’43.