Ro-61, originally named Submarine No. 72, was an Imperial Japanese Navy Type L submarine of the L4 subclass. She was in commission at various times from 1923 to 1934, and was recommissioned in 1940. Before World War II, she served in the waters of Japan. During World War II, she took part in the Battle of Wake Island and the Aleutian Islands campaign, conducting the first attack on an enemy ship ever carried out by a Japanese "Ro"-type submarine. She was sunk in August 1942.