Nirasaki is a city in Yamanashi Prefecture, Japan. As of 1 October 2020, the city had an estimated population of 28,150 in 12831 households, and a population density of 210 persons per km². The total area is 132.69 square kilometres (51.23 sq mi).

Yamanashi Prefecture is a prefecture of Japan located in the Chūbu region of Honshu. Yamanashi Prefecture has a population of 817,192 and has a geographic area of 4,465 km2. Yamanashi Prefecture borders Saitama Prefecture to the northeast, Nagano Prefecture to the northwest, Shizuoka Prefecture to the southwest, Kanagawa Prefecture to the southeast, and Tokyo to the east.