phone help

[charlosian]

hi, im new here and i have a serious question.
i live in usa and this summer i will travel to hiroshima to study abroad for a while.
i need a cell phone that can be used internationally, that i can own, not rent
i want to use it in japan and in the usa when i return so i can continue to make calls to japan on it. i have looked into gsm phones, but i noticed japan uses 3G
i have a phone in mind that i want to see if it will work as like a prepaid phone
http://www.popularelect.com/product...products_id=356
now i need to know how to set this phone up, i hear a sim card wont work for japan, but i want it set up japan use mostly, so if anyone knows good services
to make it prepaid and still work when i get back to us can i get links and more info. im really new to the international phone thing i have read the other pages about 09 and celtrek but those still seem like a lot. but i wonder if there is anything cheaper or any other new methods.
thanks