Ro-115 departed Truk on 19 May 1944 to carry supplies to Wewak, New Guinea, in support of Japanese forces fighting in the New Guinea campaign. After calling at Wewak on 27 May 1944 and unloading her cargo, she got back underway the same day and proceeded to Palau, where she arrived on 3 June 1944 to deliver secret Imperial Japanese Army documents including codebooks.
