Niimi is a city located in northwestern Okayama Prefecture, Japan. As of 28 February 2023, the city had an estimated population of 27,106 in 12626 households.and a population density of 34 persons per km2. The total area of the city is 793.29 square kilometres (306.29 sq mi)

Okayama Prefecture is a prefecture of Japan located in the Chūgoku region of Honshu. Okayama Prefecture has a population of 1,906,464 and has a geographic area of 7,114 km2. Okayama Prefecture borders Tottori Prefecture to the north, Hyōgo Prefecture to the east, and Hiroshima Prefecture to the west.