Kumamoto Castle is quite larger than most people who limit their visits to the donjon and Ninomaru think. One of my favorite places to visit is the west side, the area known as Sannomaru - nobody goes there, so it’s quiet and absolutely gorgeous and very historical (take the stairs behind the museum towards the baseball stadium). In addition to Sannomaru, there is an area set aside for trees as a bird sanctuary, all within the ancient walls, which you can inspect if your knees allow. If you really want to be a Higokko, learn this area. - William