Shall we rough it?

I'm coming to Japan in the middle of july for 2 months.Apart from sightseeing in Tokyo and Kyoto i'd also like to go hiking and camping somewhere in Japan.So far i found only groups for 2-3 day hikes..Are there any groups that take longer hikes,like for 1-3 weeks???With tents and sleeping bags and stuff???Or maybe some active individuals???

Where are you from? have you been to Japan or country with a hot and humid summer before? I'm from Ireland and I really had NO idea of what hot and humid was before I came here, I've been here 10yrs now and the only way I can deal with it is the Japanese way of denial(whacha mean? It's not that hot!!). I see in this forum that other people besides yourself and talking about hiking and camping in July and August. Thats all fine as long as you do it in the right places and are prepared to have your clothing soaked in sweat all day. The Camping part I get but Hiking in the summer...I think you are all off your minds...wait until October or November.

Nagano and Hokkaido are usually a lot cooler than the Kanto and Kansai areas in July. In Tokyo in late July just walking along the street for 5 minutes can be exhausting due to the heat and humidity, so there are definitely some areas to avoid if you want to enjoy the hiking.

I haven't heard of 3 week treks here- there wouldn't be many nature areas large enough to spend that kind of time walking in.

I recommend you go Hokkaido. If you can drive, it's great experience having camping days there.
Hokkaido is a big and has over 300 camping site so that you can't imagine that's a part of Japan.
You'll find many people camping and people taking a long ride by motorcycles.
Otherwise, go to Nagano or north Gunma. Those're not too far from Tokyo. You can get there by trains or buses. But may not big enough to spend over a week.

One notice: Though there're certainly free camping site, on the other hand there're many requires reservation and fees.
If you're asking about completely free camping in wilderness, that's may not allowed anywhere in Japan as far as I know. Camping in Japan is a kind of activity under control. (Is anyone knows about more?)

Here're examples
http://www.manythings.org/bicycle/
http://town.minamifurano.hokkaido.jp/kousya/english/03auto.c...