Shimonoseki is a city located in Yamaguchi Prefecture, Japan. As of 30 June 2023, the city had an estimated population of 248,193 in 128762 households and a population density of 350 persons per km2. The total area of the city is 716.18 square kilometres (276.52 sq mi). It is the largest city in Yamaguchi Prefecture and the fifth-largest city in the Chūgoku region in terms of population. It is nicknamed the "Fugu Capital" for the locally caught pufferfish, and is the largest harvester of the pufferfish in Japan.

The Battle of Dan-no-ura was a major sea battle of the Genpei War, occurring at Dan-no-ura, in the Shimonoseki Strait off the southern tip of Honshū. On April 25, 1185, the fleet of the Minamoto clan (Genji), led by Minamoto no Yoshitsune, defeated the fleet of the Taira clan (Heike). The morning rip tide was an advantage for the Taira, but turned to their disadvantage in the afternoon. The young Emperor Antoku was one of those who died among the Taira nobles.