The Kuma-class cruisers proved useful in combat operations ranging from the Aleutian Islands to the Indian Ocean throughout World War II.

Ōi and Kitakami were subsequently modified with ten quadruple mount torpedo launchers (a total of 40 tubes), arranged in two broadside rows of five, i.e. 20 per side.

In January 1942, Chief of Staff Rear Admiral Matome Ugaki expressed strong disapproval of the newly remodeled torpedo cruisers and urged a revision to the Navy's tactics.

The Kuma-class hull design was based on a 5,500 ton nominal displacement, with a high freeboard and light bridge structure, behind which was a tripod mast with the fire control platform and two searchlights.

[2] The propulsion system for the Kuma class was based on four axial deceleration turbines with 12 boilers, providing 90,000 hp (67,000 kW).

With improvements in geared-turbine engine technology, the Kuma-class vessels were capable of the high speed of 36 knots (67 km/h), and a range of 9,000 nmi (17,000 km) at 10 kn (12 mph; 19 km/h).

In August 1942, they were modified into fast transports, with all of the torpedo tubes removed and replaced by Daihatsu class landing craft, with depth charge racks and two Type 96 triple-mount anti-aircraft guns.

[2] After Kitakami was damaged in 1944, she was converted into a kaiten carrier, with all of her armament removed, and replaced by two Type 89 single gun turrets (fore and aft), a total of 67 Type 96 anti-aircraft guns(12 triple, 31 single), two depth charge racks and eight Model 1 Kaiten.