Kumamoto is the big city of central Kyushu, with a population of around 680,000, and its centrepiece is a castle. Kumamoto Castle was built in the early seventeenth century by the warlord Kato Kiyomasa, who was a master of fortification, and its great stone walls curve upward in a flare that is said to defeat any attempt to climb them. In April 2016 a pair of powerful earthquakes badly damaged the castle and brought down parts of its walls and roofs, and restoration work has been long and careful. The scale of the damage, and the care of the repair, are part of the city's character now.
The city has other claims on your attention. Suizenji, a landscape garden laid out in the seventeenth century, recreates the Tokaido road in miniature, with a small mound representing Mount Fuji. The local food is distinctive: thick, garlicky tonkotsu ramen, and basashi, thinly sliced raw horse meat, which is a regional specialty. The city's bear mascot, Kumamon, is everywhere, on trains, signs and souvenirs, a marketing success that has made the red cheeks famous across Japan.
As a place to start a motorcycle ride, Kumamoto is convenient. Fuel stations are everywhere, parking for bikes is manageable if you book a hotel with space, and the roads east toward Aso quickly leave the city behind. Getting out takes patience, though, because the central streets are busy with trams, buses and commuters, and the ring roads are slow at rush hour. Early on a weekend morning, you can be out of the suburbs and among the rice fields in under half an hour.
The route heads for the Aso caldera, one of the largest in the world, and the landscape changes steadily, with farmland giving way to ridges, grassland and then the volcanic bowl itself. Spring and autumn offer the best conditions, with clear air and moderate temperatures, while summer can be hot and humid, with heavy rain in June and July. Stock up on water, eat a proper breakfast, and enjoy the feeling of heading for the mountains.