Living in Japan without a cell phone is difficult, well actually not difficult, just bloody boring. When you have a city of 12million people you don't often run into friends by accident.
Of course like everything else here it take a fair amount of paperwork to get one, but annoyingly you also need to have an alien registration card before they will let you get one. I waited until I had mine then went shopping, which involved about 4 hours talking in Japanese with sales people that had to constantly keep checking what rules applied for foreigners to buy one.
Following that I decided to get a phone from softbank (they used to be vodafone and so my phone will work in NZ when I come back). I got a 2 year contract, at $15 a month, for which I get a free phone, free txt/pic/video messaging to all other softbank users, and free calling before 9pm to softbank users. Other messages cost 4 cents, and calls are 40 cents a minute.
The free calling is great, I convinced all the other foreigners I know to sign up for the same contract and so apart from my Japanese friends all my calls are free. The actually phone is pretty cool, much like a RAZR (but thinner I think, 11mm), has a 2 mega pixel camera, blue tooth, Internet, micro SD etc. Ok its not the wonderful compared to what you get here, but you've all seen what sort of phone I use in NZ, and this one was free!