I really wouldn't worry about the hornets, yes there are scary but I can't see you going to an area where they'll be. One reason they are dangerous is that they are ground dwellers and farmers will stumble across them plowing and such.
Besides there will be plenty of other bugs
Heck when I was there, two volcanoes were erupting, nothing all that serious but still.
For music and such
http://www.seekjapan.jp/ does a little round up here and there.