Cell-phone rental

Hi everyone,
i have a question regarding cell phone rental. i coming to japan for three months by myself, only to travel.
and i guess cell phone will be needed (communitcate with people i'll meet there etc.) but to use the cell phone i'm bringing with me inside japan will be really expansive. yet rent a phone for 300 yen a day is too pricey as well.
what other options do i have? are there Telephone cards that i can use? what else?

Thank you very much in advance!

Buy a prepaid phone.
You should be able to get one at Softbank Roppongi or at the Softbank shop at Narita Airport.

http://mb.softbank.jp/en/prepaid_service/

Yes, a prepaid will definitely be the cheapest mobile option assuming you will be doing some calling and emailing. Your foreign phone/plan would be cheaper assuming you don't use it, but that's probably unrealistic, and calling cards are a viable option but you won't be very accessible by going that route.

A prepaid phone will run you about 5000 yen for the handset and 3000 yen for credit (at a min of 3000 yen/month). About 300 yen of that credit can be applied to their monthly unlimited mail plan. So with minimum calling you can expect to 14000 yen to cover your three month period in Japan.

See more info here:

http://www.japan-guide.com/e/e2223.html