Karatsu is a city located in Saga Prefecture on the island of Kyushu, Japan. Its name, formed from the Japanese word roots 唐 kara, and 津 tsu (port), signifies its historical importance as an ancient trading port between Japan with China and Korea. The central area of Karatsu, which does not include the former cities and villages of Higashimatsuura District, has a population of 78,386.