This class consists of KAZAN MARU, renamed UNKAI MARU No. 3 in Feb ’31, and TOKO MARU, first renamed KIBI MARU No. 15 in 1921 and ultimately renamed UNYO MARU No. 3 in 1928. Both ships were completed in 1919 for various shipping companies. UNYO MARU No. 3 was requisitioned by the IJA and served as Army transport No. 709 until being torpedoed and sunk off Shanghai in Jul ‘42. UNKAI MARU No. 3 was requisitioned by the IJN in Apr ’42 and converted to an auxiliary stores ship. In Nov ’42, at Yokohama harbor, she was destroyed by the explosions of German tanker UCKERMARCK.