SHIMANE MARU was laid down and launched as a Type 1TL Standard Merchant tanker, but completed by the IJN as an ASW escort carrier for the IJA. She was envisaged as an aircraft-carrying tanker which could also be used for training. In the event, because of lack of pilots, planes and fuel, she never became operational. In July 1945, British Task Force 37 bombed and sank her in the Inland Sea.

Sister 1TL OTAKISAN MARU was launched on 14 Jan '45, but never completed. Plans also called for OTAKISAN MARU to be converted to an escort carrier. At war's end she was 70 percent complete, but on 25 Aug '45, she drifted onto an aerial mine at Kobe and sank.