Karatsu is a city situated in Saga Prefecture on the island of Kyushu, Japan. Its name is derived from the Japanese word roots "kara" (唐) and "tsu" (津), which signify its historical role as an ancient trading port connecting Japan with China and Korea.
As of June 1, 2024, the city covers a total area of 487.60 km² (188.26 sq mi) with an estimated population of 114,695 residing in 51,375 households. The population density is approximately 200 persons per km². Notably, the city shares the same Chinese characters for its name as the city of Dangjin in South Chungcheong Province, South Korea.