Sorry writing answer in English. The Kumamoto castle area is now almost off limits and partly allowed to enter. You can view seriously damaged castle and stone walls at Kato-shrine area. Jyosaien (restaurants and souvenir shops) and Wakuwaku-za (amusement theater) are open everyday. Both are near south of the castle.

Castle guided tour has been resumed since 17th June.Tour route is temporary so far.

You can goto ticket office at main entrance by taxi or bus. After that, you can goto Castle without stairs but slightly upward slope. There is a short but very steep slope when you get closer to the castle. My parents in law who are 7x years old could manage to walk without much difficulty. However, if you want to go to the top of the castle, only stairs available! My father in law did walk to the top of the castle while my mother in law didn't. I don't think there's special facilities for disabled.