Semboku is a city located in Akita Prefecture, Japan. As of 31 January 2023, the city had an estimated population of 24,045 in 10,398 house…Semboku is a city located in Akita Prefecture, Japan. As of 31 January 2023, the city had an estimated population of 24,045 in 10,398 households, and a population density of 22 persons per km. The total area of the city is 1,093.56 square kilometers.