The Shokaku class consisted of two aircraft carriers built for the Imperial Japanese Navy (IJN) in the late 1930s. Completed shortly before the start of the Pacific War in 1941, the Shokaku and Zuikaku were called "arguably the best aircraft carriers in the world" when built. The two Shokaku-class carriers were ordered in 1937 as part of the 3rd Naval Armaments Supplement Program. No longer restricted by the provisions of the Washington Naval Treaty, which had expired in December 1936, and with relaxed budgetary limitations, the IJN sought qualitative superiority over their foreign counterparts. Drawing on experience with their existing carriers, the Navy General Staff laid out an ambitious requirement for a ship that equaled the 96-aircraft capacity of the Akagi and Kaga, the speed of Hiryu and the defensive armament of Kaga. The new ship was also to have superior protection and range over any of the existing carriers.
-Wikipedia