In December 1942, with the first of the
Oyodo-class light cruisers about to enter service, the IJN decided to modify the design so as to have a vessel of a similar design function as an actual light cruiser, not the submarine squadron flagships the
Oyodos were supposed to be. The result was that the large hangar and catapult astern were removed and replaced with a more conventional aft superstructure and a third triple 6.1-inch turret. Two more twin 3.9-inch guns were added to the secondary armament; one forward and one aft. The first of the new class,
Isoshima, was laid down at the end of January 1943, with sister ships
Yasoshima,
Aoshima, and
Yakushima following in April, June, and August 1943, respectively. The four ships were all launched between June and December 1944, and entered service from June 1945 - January 1946.