Shimonoseki is a city located in Yamaguchi Prefecture, Japan. As of 30 June 2023, the city had an estimated population of 248,193 in 128,762 households and a population density of 350 persons per km2. The total area of the city is 716.18 square kilometres. It is the largest city in Yamaguchi Prefecture and the fifth-largest city in the Chūgoku region in terms of population.