Nachi was the second of four Myōkō-class heavy cruisers built for the Imperial Japanese Navy — the other ships of the class being Myōkō, Ashigara and Haguro. She was named after a mountain in Wakayama Prefecture.
The ships of this class displaced 13,300 long tons (13,500 t), were 201 m (659 ft) long and capable of 36 kn (67 km/h; 41 mph). They carried two floatplanes, their main armament was ten 203 mm (8.0 in) guns in five twin turrets. This was the heaviest armament of any cruiser class in the world, at the time they were built.
Nachi was laid down at the Kure Naval Arsenal on 26 November 1924, launched and named on 15 June 1927, and was commissioned into the Imperial Navy on 26 November 1928. Her service in World War II started in the Dutch East Indies, where she engaged the enemy off Makassar on 8 February 1942. She played a key role in the Battle of the Java Sea on 27 February, and was involved in the sinking of HMS Exeter and Encounter in another action off south Borneo on 1 March.
Nachi then moved to the Aleutian Islands where she was engaged in the diversionary attack on the islands on 3 June; she was back in the Aleutians when she was damaged on 26 March 1943 in the battle of the Komandorski Islands, and was engaged in an action at Kiska in July 1943.
By October 1944, she was in the Philippines and took part in the Leyte Campaign, as part of a cruiser force under the command of Vice Admiral Kiyohide Shima. Nachi was damaged in the Battle of Surigao Strait on 25 October 1944 after a collision with Mogami.