Buy a cellphone or rent one?

Hi! I will be going to Japan for nine months and I was wondering If I should buy a new (japanese) mobile phone or just rent one. I have seen some websites where they rent SIM cards but it is expensive so I was thinking maybe of getting a Japanese phone. I would like to have 3G... Would it be better to buy one or rent it? I hope someone could help me!Thankyou

For 9 months, the cheapest would be to get a softbank prepaid phone (calling and mail only) and then supplement with paid/free wifi spots if necessary. Otherwise look into using a prepaid provider like bmobile. They have a variety of data only, or data/voice plans so you should be able to find something to suit your needs.

http://www.bmobile.ne.jp/lineup.html

You can get a Softbank prepaid phone at Don Ki (Don Quiote) stores for just the price of a Y3,000 load card, which you would have to buy anyhow.

This only works if you are not a tourist, since you need some kind of Japanese ID besides a foreign or Japanese passport.

The big Don Ki store in Akihabara has them, or at least as late as last October.

Softbank has a nice English language user manual for their prepaid services, though you might have to go to a big Softbank store to get one.

Thank you guys!!! That really helped me a lot!