Shimonoseki (shēˈmōnōsāˌkē) [key], city (1990 pop. 262,635), Yamaguchi prefecture, extreme SW Honshu, Japan. An important port and fishing center on Shimonoseki Strait, it is opposite Kitakyushu, with which it is connected by bridge and tunnel. Shimonoseki is a railroad and industrial center, with engineering works, shipyards, and metal and chemical plants. It is also a port, with ferry connections to Busan (Pusan), South Korea. In the city is Akamagu, a 12th-century shrine dedicated to Emperor Antoku and to the Taira clan, which was defeated at Shimonoseki by the Minamoto clan in the famous naval battle of Dan-no-ura. In 1864 a fleet of U.S., British, French, and Dutch ships bombarded the port in retaliation for hostile acts of the Choshu clan. The Treaty of Shimonoseki, which ended the Sino-Japanese War, was negotiated and signed in 1895. The Shimonoseki Aquarium is the largest in Japan.