During the Battle of the Eastern Solomons on 27 August, "Mutsu", assigned to the support force, fired four shells at enemy reconnaissance aircraft, the first and only time her guns were fired in anger during the war. Following her return to Truk on 2 September, a group of skilled AA gunnery officers and men were detached to serve as instructors to ground-based naval anti-aircraft gunners stationed in Rabaul. During October "Mutsu" off-loaded surplus fuel oil to the fleet oil tanker "Kenyo Maru", allowing the tanker to refuel other ships involved in Guadalcanal operations. On 7 January 1943, "Mutsu" steamed from Truk via Saipan to return to Japan together with the carrier , the heavy cruiser and four destroyers. "Mutsu" left Hashirajima for Kure on 13 April, where she prepared to sortie to reinforce the Japanese garrisons in the Aleutian Islands in response to the Battle of the Komandorski Islands. The operation was cancelled the next day and the ship resumed training.