Kōfu is the capital city of Yamanashi Prefecture, Japan. As of 1 April 2019, the city had an estimated population of 187,985 in 90,924 household…Kōfu is the capital city of Yamanashi Prefecture, Japan. As of 1 April 2019, the city had an estimated population of 187,985 in 90,924 households, and a population density of 880 persons per km². The total area of the city is 212.41 square kilometres.