The Ro-100 class was a medium-sized, coastal submarine derived from the preceding Kaichū type.

[1] For surface running, the boats were powered by two 500-brake-horsepower (373 kW) diesel engines, each driving one propeller shaft.

[4] Upon commissioning, Ro-112 was attached to the Kure Naval District and was assigned to Submarine Squadron 11 for workups.

[4] She departed Kure, Japan, on 26 December 1943 bound for Surabaya on Java in the Japanese-occupied Netherlands East Indies.

[4] She was surfacing in the Java Sea north of Bali off Cape Bungkulan at 08°02′S 115°25′E / 8.033°S 115.417°E / -8.033; 115.417 on 19 March 1944 when the United States Navy submarine USS Rasher (SS-269) sighted her.

"[4] At 11:49, Rasher fired four Mark 14 Mod 3 torpedoes at Ro-112, but Ro-112 turned to port and evaded them.

[4] While at sea, she was reassigned to Patrol Unit B on 29 April 1944 and ordered to operate south of Woleai′s Mereyon Island.

[4][5] The picket line was tasked with providing warning of any move toward the Palau Islands by Allied invasion forces.

[4] When the Japanese 6th Fleet intercepted and decrypted an American signal on 27 May 1944 reporting the destruction of the submarines, it sent a warning message that prompted Ro-112′s commanding officer to move her to a new position 100 nautical miles (190 km; 120 mi) northwest of the area in which Ro-112 had been patrolling.

[4] She subsequently departed her patrol area and set course for Truk, which she reached on 8 June 1944.

[4] On 4 February 1945, the 6th Fleet ordered Ro-112 and the submarines Ro-46, Ro-113, and Ro-115 to proceed to Takao, Formosa, unload their reserve torpedoes and deck gun ammunition there, and then head for Batulinao on the northern coast of Luzon to rescue Japanese pilots stranded in Luzon's Aparri area and transport them to Takao.

[4] Ro-112 was on the surface in the Luzon Strait in the vicinity of Camiguan Island north of Luzon on the evening of 11 February 1945 when the U.S. Navy submarine USS Batfish (SS-310) detected her on radar at 18:51 bearing 310 degrees from Batfish at a range of 8,000 yards (7,300 m).

On 20 February 1945, the Imperial Japanese Navy declared Ro-112 to be presumed lost in the Luzon Strait with all 61 men on board.