Tosashimizu is a city located in the southwest of Kōchi Prefecture, Japan. As of 31 July 2022, the city had an estimated population of 12,407 in 7004 households, and a population density of 47 persons per km2. The total area of the city is 266.34 square kilometres (102.83 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.