Second vacation to Japan - But where to go?

[Hazuki]

I'm planning my second vacation to Japan. I was there recently and celebrated new year's eve. Spent 3 weeks in Tokyo but party most of the days so regret I didn't do more cultural things like going to sumo. Anyway I was thinking of going to Tokyo again because of some friends there, but then again I would like to see some other cities in Japan too.

The thing is that I planned to stay for a month this time, between 15 of July to 15 of August. Would like to see some Natsu Matsuri or other festivals but donno where to look for tickets etc, anyone know where to start? Also I was wondering if it's easy to travel between Osaka, Kobe, Kyoto and Tokyo? Would it be really expensive or is there some railway pass that I can use in most parts of Japan?

I have allot of more thins to explore in Tokyo tho, but as I said Tokyo is a interesting place but there are other places to visit too

If anyone have a recommendation where to go I really appreciate it!