Ōryoku Maru (鴨緑丸, named after Yalu River) was a Japanese passenger cargo ship which was commissioned by the Imperial Japanese Navy during World War II as a troop transport and prisoner of war (POW) transport ship.

Oryoku Maru left Manila on December 13, 1944, with 1,620 prisoners of war (including 1,556 American, 50 British and Dutch, 7 Czech, 4 Norwegians and several other nationalities) packed in the holds, and 1,900 Japanese civilians and military personnel in the cabins.

[7] As she neared the naval base at Olongapo in Subic Bay, US Navy planes from USS Hornet attacked the unmarked ship, causing it to sink on December 15.

A colonel, in his official report, wrote: The survivors of the sinking were held for several days in an open tennis court at Olongapo Naval Base.

Shuske Wada, whose charges paralleled those of Toshino, was the official interpreter for the guard group.

Wada was found guilty of causing the deaths of numerous American and Allied prisoners of war by neglecting to transmit to his superiors requests for adequate quarters, food, drinking water, and medical attention.