One of the things I love about big cities is the convenient public transporation. Kumamoto has buses, taxi cabs, trains, and trams. The tram is my favorite because it goes up and down the center of town, one end to the next. You never have to worry about getting lost or having to connect to another tram. This is considering you only plan on going downtown for shopping or a movie. Trains can take you anywhere else but learning all the stops is difficult, especially when all the signs are in Kanji.
I also like the trams for their affordability. It only costs a mere $1.50 for me to go 6 miles into town. I love train cultures, every is just more relaxed and there is no or hastle of having to drive the busy streets. Also, they are always on time (unlike the buses which can often be 15 to 20 minutes behind schedule) and there is a new trolly every ten to fifteen minutes. They're like clock work I tell you! Plus they are air conditioned; for me this is a most important feature. Not being used to Kumamoto's super humid and awefully hot weather escaping into a air cooled trolly is one of the surest ways to escape the smoldering Japanese summer for a few blocks. Just enough time to duck and doged narrowly saving one's self from heat stroke. Trust me, I know from personal experience.