Considering the Hotel Nikko Kumamoto in Kumamoto?
A VT member wrote the following comment about visiting Kumamoto:
Visit a live VolCanO! Mt. Aso by dlandt
Not far from Kumamoto is the real live active volcano, Mt. Aso, one of several on Kyushu. A trip to Mt. Aso is fairly simple, you drive up into the mountains, through the towns of the caldera and then up through Aso Park to the cable car. Ride the cable car up right up to the rim. There are three main viewing areas, though when I visited only one was open due to volcanic gasses. If that weren't a reminder enough, scattered around the rim are mushroom shaped pill boxes so people can take cover from spewing ash and cinders when the volcano gets REALLY active. A third reminder of the power of the volcano lay in the altars the Japanese set up. About the altars were gifts to the volcano God to keep her from waking up.
Mist and gas makes it a bit difficult to see the lava lake, but every once in a while the mist clears and you get a look. The smell of sulphur permeates the air all around the rim and you can buy bags of sulphur or figurines made from volcanic ash from various vendors. The cable car area boasts a number of restaurants and souvenier stores, as does the volcanic museum below.