WebKumamoto (熊本市, Kumamoto-shi) is the capital city of Kumamoto Prefecture on the island of Kyushu, Japan. As of June 1, 2019, the city has an estimated population of 738,907 and a population density of 1,893 people per km 2. The total area is 390.32 km 2 . Greater Kumamoto (熊本都市圏) had a population of 1,461,000, as of the 2000 census.