In response to the invasion of Attu Island on 11 May, the Second Carrier Division departed Truk, accompanied by three battleships and two heavy cruisers and reached Japan on 25 May. The Americans recaptured Attu before the fleet could depart to counter-attack. Now the flagship of the Second Carrier Division under Rear Admiral Munetaka Sakamaki, "Hiyō" departed Yokosuka on 7 June with "Junyō" en route for Truk. Later that evening, the ship was torpedoed by the submarine off Miyakejima. Hits in the starboard bow and boiler room knocked out all power but she managed to return to Japan the following day after restoring power. "Hiyō"s fighters were flown to Truk by 15 July and assigned to the light carrier , as were Sakamaki and his staff. While being repaired at Yokosuka until 15 September, more 2.5 cm Type 96 AA guns were installed, and Sumikawa was relieved by Captain Tamotsu Furukawa on 1 September. Two months later, "Hiyō"s air group was reconstituted in Singapore with 24 Zeros, 18 D3As and 9 B5Ns; the ship departed Japan for Singapore on 24 November. She arrived on 3 December, loaded her air group and was almost immediately assigned duties as an aircraft ferry. On 9 December, "Hiyō" left Singapore en route for Truk with several deliveries on the way. The ship arrived there on 22 December and disembarked her aircraft before proceeding to Saipan to deliver more aircraft. The air group was transferred to Kavieng and later Rabaul to provide air cover for Japanese operations there where the fighters claimed 80 victories in exchange for 12 losses.