"Ibuki"s trials displacement increased to and the additional weight increased her draft to .Initially, the ship was to have a very light armament of only 22 triple 2.5-centimeter gun mounts, controlled by eight Type 95 fire-control directors, but this was modified in 1944 to substitute four 60-caliber 8 cm (3 in) Type 98 dual-purpose guns, mounted in two twin-gun turrets, and four 28-tube launchers for anti-aircraft rockets for six of the triple 25-millimeter gun mounts and two directors (now Type 4s).