Around 1940, the IJN had begun planning its next class of heavy cruisers, referred to as the 'Type A'. However, the Naval General Staff had several points of contention with the design, with the fact that the four quadruple torpedo tubes were placed at the very stern of the ship - right above the propellers - being at the top of the list. Due to the squabbling between the Naval General Staff and the Naval Construction Corps, the design was shelved with the outbreak of war, but in February 1942, it was pulled out of mothballs and looked over once again. The designers managed to fix the placement of the torpedo tubes, and finally the design was approved in March 1942. The first ship (
Ibuki) was laid down in April 1942, with three sister ships commencing construction by September. By the time they began joining the fleet in late May 1944, they were welcome additions, for by that time the IJN had lost eight of its twenty pre-war heavy cruisers. With their four triple 8-inch turrets, the
Ibukis were the most heavily-armed IJN CAs ever built.