on 16 June, she underwent a refit and began her second patrol on 17 July. She again sailed to Guam, where she stayed on 1 and 2 August, before continuing on to the Sea of Japan. On 10 August, Torsk passed through the minefields in the Tsushima Strait, and the next day, she found and took aboard seven Japanese sailors from the merchant ship Koue Maru that had been sunk four days earlier. Later on the 11th, the submarine entered her patrol area. While patrolling off Dogo Island the next morning, she located a small freighter and sank her with a submerged torpedo attack. Off Ando Saki on 13 August, Torsk found several small fishing boats and another small freighter; she sank the latter and later that day, attempted to sink another cargo vessel in Wakasa Wan but her torpedoes missed. 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. At around 12:00, a second Kaibōkan arrived in the area to hunt for Torsk; the latter fired a second Mark 28 torpedo and then dove deep to evade any depth charge attacks. After reaching a depth of , she launched a Mark 27 torpedo, a passive acoustic torpedo. Shortly thereafter, the hydrophone operator detected a large explosion; this was the Mark 28 striking the Kaibōkan, and a minute later the Mark 27 struck the vessel as well. This proved to be the last Japanese warship to be sunk in World War II, as the Japanese government announced it would surrender the next day. Additional patrol vessels arrived in the area, and their presence, coupled with that of patrol aircraft, compelled Torsk to remain submerged for more than seven hours. She then surfaced and proceeded toward the Noto Peninsula. After receiving word of Japan's surrender on 15 August, Torsk continued patrolling the Sea of Japan, conducting surveillance of Japanese installations and destroying any naval mines she encountered. On 1