Imperial Headquarters wanted more carriers despite the fact that there were few pilots available. There were two Type 1TL/ four oil tankers then under construction and it was decided to convert them into convoy escorts.
There was a single elevator.
A single horizontally mounted funnel was put on the starboard side towards the rear of the ship.
There was a hangar located amidships.
As there was almost no oil left in Japan, in February 1945 work on the Shimane Maru was stopped and work to convert her into a coal burning cargo ship was started. Similarly the Otakisan Maru was to start conversion into a coal burner but she was sunk before it began.
Due to the lack of oil it was decided to convert the ships into coal burners but that was cancelled and it was decided to convert them back into oil tankers. Before this could start the Shimane Maru was sunk. The Otakisan Maru was also to be converted to coal, this was cancelled and it was decided to convert her back to an oil tanker. This didn't happen as she was sunk before work commenced.