J-Phone, a Vodaphone unit, sells a prepaid mobile.
http://www.j-phone.com/english/servi...syu/index.html
I would think this with a combination of a calling card is the best option for mobility and cost-effectiveness, if not most economical.
Go2Call is 5 cents per minute (1 yen per call to 800 numbers) to the U.S. but you need a PC and a headset with a microphone.
[This message has been edited by Chiangi (edited 07-31-2003).]