My wife and I will be spending 5 days in Kyushu, travelling from Osaka. We would prefer to base ourselves in a central location and travel to other centres (by rail mostly) on a daily basis, probably in the northern part of Kyushu. Please recommend a suitable base .e.g. Would Kumamoto be a practical place to travel to most other northern centres such as Beppu, Nagasaki etc. It seems to be on a main rail line? Thanks.