Nagato is a city in Yamaguchi Prefecture, Japan. As of 28 February 2023, the city had an estimated population of 31,518 in 15537 households …Nagato is a city in Yamaguchi Prefecture, Japan. As of 28 February 2023, the city had an estimated population of 31,518 in 15537 households and a population density of 88 persons per km². The total area of the city is 357.31 square kilometres.