Kumamoto, situated roughly in the center of Kumamoto Prefecture, is the government and economic center of the prefecture. Personal belongings of its lords in different generations, armaments of olden days, etc. are displayed inside the castle tower for visitors to peruse. To the southeast of the castle, the Suizenji Joju-en Garden is a popular place of relaxation for people of Kumamoto.
More info: https://www.japan.travel/en/spot/638/