June 1942. While still fitting-out, Shōhō was assigned to the Fourth Carrier Division of the 1st Air Fleet on 22 December 1941. On 4 February 1942, she ferried aircraft to Truk, where she remained until 11 April before returning to Yokosuka. In late April 1942, Shōhō was assigned to Operation MO and arrived in Truk on 29 April. The following day, she departed Truk in company with four heavy cruisers and they formed the Main Force of the operation. Due to aircraft shortages, her aircraft complement consisted of only four obsolete Mitsubishi A5M "Claude" and eight modern Mitsubishi A6M2 "Zero" fighters plus six Nakajima B5N2 "Kate" torpedo bombers. Covering the other elements of Operation MO was the Striking Force that consisted of the fleet carriers and . Coral Sea, Midway, and Guadalcanal After covering the landings on Tulagi on 3 May, Shōhō headed north to cover the invasion convoy the next day and was not present when aircraft from the American carrier attacked Japanese shipping at Tulagi. This air strike confirmed that at least one American carrier was in the vicinity, but the Japanese had no idea of its location. They launched a number of reconnaissance aircraft the following day to search for the Americans, but without result. US Army Air Force (USAAF) aircraft spotted Shōhō southwest of Bougainville Island on 5 May, but she was too far north to be attacked by the American carriers, which were refueling. That day, Rear Admiral Frank Jack Fletcher received Magic intelligence that placed the three Japanese carriers known to be involved in Operation MO near Bougainville, and predicted 10 May as the date of the invasion. It also predicted airstrikes by the Japanese carriers in support of the invasion several days before 10 May. Based on this information, Fletcher planned to complete refueling his ships on 6 May and move closer to the eastern tip of New Guinea to be in a position to locate and attack Japanese forces on 7 May. American reconnaissance aircraft reported two Japanese heavy cruisers northeast of Misima Island in the Louisiade Archipelago off the eastern tip of New Guinea at 0735 and two carriers at 0815 on 7 May. An hour later Fletcher ordered an airstrike launched, believing that the two carriers reported were Shōkaku and Zuikaku. and Yorktown launched a total of 53 Douglas SBD Dauntless dive bombers and 22 Douglas TBD Devastator torpedo bombers