Nachi (Myoko class of heavy cruisers) was 669 feet in length, with a beam of 64 feet, and draft of 20.9 feet, and was capable of 35.5 knots.Propulsion was by 12 Kampon boilers driving four sets of single-impulse, geared turbine engines, with four shafts turning three-bladed propellers. The ship was armored with a 102 mm side belt, and 35 mm  armored deck, but the bridge was not armored.

Nachi’s main battery was ten 20 cm/50 3rd Year Type naval guns, the heaviest armament of any heavy cruiser in the world at the time, mounted in five twin turrets. Her secondary armament included eight 12.7 cm/40 Type 89 naval guns in four twin mounts on each side, and 12 Type 93 Long Lance torpedoes in four triple launchers positioned below the aircraft deck. Nachi was also equipped with an aircraft catapult and carried up to three floatplanes for scouting purposes.