On the night of 9 May 1943, "Wahoo" proceeded up the coast with the intention of closing Kone Saki. Radar picked up two targets, soon identified as a large tanker and a freighter in column, evidently making the night run between ports without an escort. The submarine fired a spread of three torpedoes at the tanker and immediately thereafter a three torpedo spread at the freighter. "Wahoo" had two successful hits, and both ships went down; "Takao Maru" () and "Jinmu Maru" ().