Usuki is a city located on the east coast of Ōita Prefecture, Japan. As of 1 October 2023, the city had an estimated population of 34,155 in 14538 households, and a population density of 120 persons per km². The total area of the city is 868.02 km2 (335.14 sq mi). It is famous for its Usuki Stone Buddhas, a National Treasure, and its soy sauce production.

Ōita Prefecture is a prefecture of Japan located on the island of Kyūshū. Ōita Prefecture has a population of 1,136,245 and has a geographic area of 6,340 km2. Ōita Prefecture borders Fukuoka Prefecture to the northwest, Kumamoto Prefecture to the southwest, and Miyazaki Prefecture to the south.