Where to go and what to see?

I will be soon going to tokyo and plan on having a life changing trip to backpack across japan, I dont know what to see or where to start my journey. Any pointers will help me out.

A pointer:
http://www.japan-guide.com/e/e623a.html

With out knowing what you want to do, brief history of yourself, I (we who would help) don�ft know what to suggest

Uses the link Uji gave, but if you want more help give us some more information.
Length of time
What Season (month(s) of year)
Number of people
Any site�fs of interest (historical/religious/nature/etc)
Sleeping location (Camp site/hostel/hotel/mix)

The more information the better.

Length of time- havent yet decided could be from months to years
What Season (month(s) of year)- Hopefully around this August
Number of people- Myself and maby one other
Any site�fs of interest (historical/religious/nature/etc)- Any and all
Sleeping location (Camp site/hostel/hotel/mix)- Anywhere im also bringing a tent

I just wish to go from place to place and see where the wind takes me for a while, im up for anything and everything.

Still very hard to give advice with such a broad trip planned.

Months to Years? What are you planning on doing for a visa considering most countries you will be eligible for 90 days, some you will get 180.

I would consider locking down some major cities you want to visit then try and flesh something out there.

Tokyo, Kobe, Kyoto, Hokkaido would be some places to think about ... again ALL very different and full of culture and religion.

Happy to asnwer more questions if yuo can narrow things down a bit.

If you're really gonna be going for months and maybe more, then why not try something like this (walking the length of Japan):

http://video.google.com/videoplay?docid=3067683435545761102

I'm just not sure about your choice of time, August and September will be hell for you with the heat, unless you start in Hokkaido and work yourself southwards maybe.

As for spots to visit, I recommend that you research on your own until you know more precisely what route you'll be taking and what things you're adamant about seeing. When you've done that you should come back and ask for hints.

You don't want us to do all the planning for you, this is after all supposed to be your dream trip.

Well I apologize for being a bit scarce in my answers, but in reality im not sure myself about half of them.

Thank you for the vido link, that helped. Also why shouldent I start that time of year? and just another question that I cant research correctly, but what are some of the longest time spanning visas?

and just another question that I cant research correctly, but what are some of the longest time spanning visas?

Depends on what country you are from. If you only plan on traveling then you typically only qualify for a 90 tourist visa.

Don't be afraid to just sit back in a location in Japan and just take in the sights and absorb the atmosphere, even if you look like an idiot, you'l be having fun :P

most tourists can only get a 90 days visas.some get shorter ones, depending on your country. August is very hot and humid.
you really need to have a much better idea of where you want to go. Only you can decide, we can't do it for you, only tell you if your plans are practical, how to best go from here to there etc. Please read guidebooks, read all the "pages" on this site (at the top)about travel, living, Japan A to Z etc.
I would recommend that you focus on one region only as there are lots of things to see in each region. I, and likely others, don't quite now what you mean by life-changing experience? going to war or even enrolling in the army would definitely be but travelling? unless you have never been out of your comfort zone, never experienced trying to communicate with others without knowing their language?