Nankoku is a city located in Kōchi Prefecture, Japan. As of 31 July 2022, the city had an estimated population of 46‚459 in 22499 households and a population density of 370 persons per km2. The total area of the city is 125.30 square kilometres (48.38 sq mi).

Kōchi Prefecture is a prefecture of Japan located on the island of Shikoku. Kōchi Prefecture has a population of 669,516 and has a geographic area of 7,103 km2. Kōchi Prefecture borders Ehime Prefecture to the northwest and Tokushima Prefecture to the northeast.