Tōkamachi is a city located in Niigata Prefecture, Japan. As of 1 July 2019, the city had an estimated population of 28,728 in 19,823 households, and a population density of 86.3 persons per km². The total area of the city was 590.39 square kilometres (227.95 sq mi), although some borders of the city are not well defined. Tōkamachi derives its name from the fact that a market was held every tenth day of the month. Similarly, the nearby former town of Muikamachi had its own local market held on days ending in six each month.

Niigata Prefecture is a prefecture in the Chūbu region of Honshu of Japan. Niigata Prefecture has a population of 2,131,009 and is the fifth-largest prefecture of Japan by geographic area at 12,584.18 km2 (4,858.78 sq mi). Niigata Prefecture borders Toyama Prefecture and Nagano Prefecture to the southwest, Gunma Prefecture to the south, Fukushima Prefecture to the east, and Yamagata Prefecture to the northeast.