On 30 November 1942, with conversion and repairs complete, "Ryūhō" was officially assigned to the 3rd Fleet. On her first mission on 11 December, under the command of Captain Yoshio Kamei, she was sent to the Japanese naval base at Truk escorted by the destroyer . Her normal aircraft complement consisted of 15 Mitsubishi A6M "Zero" fighters and 16 Aichi D3A "Val" dive bombers, but for this mission, she was carrying 20 light bombers with their pilots and crews on a ferry mission. At 09:10 on 12 December, she was hit by a single torpedo on the starboard side from the American submarine near Hachijojima, and was immediately forced to return to Yokosuka for emergency repairs, and remained out of operation until early 1943.