[Nyororin]

You know, I just glanced in here and laughed a bit.
WWOOF is to do with staying on farms, dealing with agriculture, animals, etc.

And yet you want to do that near/in Tokyo? You do realize that Tokyo isn`t exactly famous for it`s farmland, right?
Of course you aren`t going to find many places in or around Tokyo. There just isn`t as much available land for that sort of thing being as it`s a huge city.

I can`t offer any recommendations as to what would be a good plan for staying in/around Tokyo - as the cost of living is high there and people have a lot less space to just freely give out.

My suggestion is to give up on Tokyo, and go wherever. You`ll learn much more, see much more, and most likely have a better experience.