Japan Guide
Here’s a link which I find very useful.
They have a quite extensive as well as a good source of inspiration of what to do outside of the Tokyo area. Not to mention it often gives clear information about how to get tickets or how to travel to the place mentioned.
Hope this helps.
EDIT
Here’s another useful link on the same page but easier to manage
And yet another for those more interested in night-life and the like
Updated this with one more link