The Ibuki-class cruisers were ordered in the Rapid Naval Armaments Supplement Programme of November 1941, and they were slightly improved versions of the preceding Mogami class after those ships had been upgraded during the late 1930s.

After the heavy losses suffered in the Battle of Midway in early June 1942, the IJN reorganized its current building programs to emphasize aircraft carrier construction.

[1] The navy considered completing Ibuki as a high-speed replenishment oiler, but decided to convert her into a light aircraft carrier[2] on 25 August.

The turbines were intended to produce a total of 152,000 shaft horsepower (113,000 kW) to give the ships a speed of 35 knots (65 km/h; 40 mph).

They carried enough fuel oil to give them an estimated range of 6,300 nautical miles (11,700 km; 7,200 mi) at 18 knots (33 km/h; 21 mph).

[8] The Ibuki-class ships were intended to be armed with four rotating quadruple 61 cm (24 in) Type 92 torpedo tube mounts, two on each broadside.

The ship carried 24 Type 93 torpedoes, commonly referred to in post-war literature as the "Long Lance", 16 in the tubes and eight in reserve.

Quick-reloading gear was installed for every mount that allowed the reserve torpedoes to be loaded in three to five minutes in ideal conditions.

The ship now could carry enough oil for an estimated range of 7,500 nmi (13,900 km; 8,600 mi) at a speed of 18 knots (33 km/h; 21 mph).

[12] The ship's air group was intended to consist of 27 aircraft, 15 Mitsubishi A7M Reppū (Allied codename: "Sam") fighters and a dozen Aichi B7A Ryusei ("Grace") dive/torpedo bombers.

The ship was launched on 21 May and construction was suspended in July until the IJN decided to convert her into a light aircraft carrier the following month.

Work continued until 16 March 1945, but it was halted when she was 80% complete to concentrate on the construction of small submarines needed to defend Japan against an American invasion.