The Ryoyo Maru (良洋丸, Ryōyō Maru) was a 5,974-gross register ton passenger ship that was built by Kawasaki Dockyard Company, Kobe, for Tōyō Kisen Kabushiki Kaisha, launched in 1931.
She was requisitioned by the Imperial Japanese Army and fitted out as a fast troop transport.
[3] On 4 March 1944, she was damaged when struck by a large wave and driven aground off Matsuwa Jima, in the Kuril Islands.
Ryoyo Maru was anchored in a harbour along the Kuril Islands, when she was struck by a torpedo from USS Tautog on 2 May.
She settled in 24 feet (7.3 m) of water, decks awash at 48-04N, 153-16E.