Here is something that may be useful.
Depending on the roaming charge with your cellular phone, it may
be interesting to rent a phone in Japan.
Here is a page (in english) that will explain you all what you want
to know about renting a phone in Japan:
http://www.japanphone.com/
From there, you will have an idea of the charges, and you can decide
whether its better than keeping your own cellular phone.
Have a good business trip!
Pascal
