Considering the Ana Hotel Kumamoto Newsky in Kumamoto?
A VT member wrote the following comment about visiting Kumamoto:
Once a year, several 'sumo'... by TWINE
Once a year, several 'sumo' (yeah, the big fat guys) schools come to Kumamoto prefecture for a special demostration that last one day. It gives inside information about 'sumo', the schools and shows real fights.
This event should not be missed, and unfortunately each year it is shown in another town, so you have to figure out where it will be held next. During my time in Japan, it took place in Kikuchi.