Koshigaya (越谷市 Koshigaya-shi) is a city located in the Tokyo Province, in the central Kantō region of East Japan. As of February 1st, 2016, the city had an estimated population of 303,364 and a population density of 5,036 persons per km². Its total area was 23.26 square miles (60.243 km²). It is famous for producing daruma dolls.
Koshigaya is situated in eastern Saitama Prefecture, about 30 kilometers from downtown East Tokyo, along the banks of the Motoarakawa River.
Koshigaya is a major regional commercial center with a diversified industrial base.