After "Taiyō"s repairs were completed in November 1943, she was transferred to the Grand Escort Command and began a refit that lasted until April 1944. "Un'yō" was also transferred to the Grand Escort Command in December 1943, but she continued her ferry missions to Truk. While returning from one, the ship was torpedoed in the bow on 19 January 1944, causing it to sag. While en route to Japan, part of her bow broke off in a storm and caused the forward end of the flight deck to collapse. She had to steam stern-first to Yokosuka for repairs that were completed at the end of June. "Taiyō" began escorted convoys to Manila, Formosa and Singapore after her refit was completed. She was torpedoed by the submarine on 10 August which caused her aft avgas tank to explode; the carrier sank about half-an-hour later with heavy casualties. "Un'yō" was only able to escort one convoy before she was sunk. During a return voyage from Singapore on 17 September, she was torpedoed by the submarine . The torpedoes knocked out her steering gear and engines; a storm developed that night and caused severe flooding that caused her to sink the following morning.