On 14 August, she encountered a medium-sized cargo ship accompanied by a "Kaibōkan" type escort vessel steaming off （）. When the two ships approached Kasumi Ko at 10:35, "Torsk" launched a new, experimental Mark 28 torpedo, an acoustic homing torpedo, at the "Kaibōkan". The torpedo struck the ship and blew a hole in the stern, bending it up at a 30-degree angle and causing it to rapidly sink. "Torsk" then attempted to torpedo the freighter as it entered the harbor, but the torpedoes missed, possibly because they struck uncharted coral reefs.