There are quite a few options.
People have mentioned:
. renting a phone in Japan
. renting a Japanese USIM card in Japan and using it in an unlocked 3G
phone that supports the 2100 band (European 3G phones do this, most
US 3G phones do not).
You can also roam with your Verizon service in Japan if you have Global
roaming service (meaning that you have a Verizon SIM card for global
roaming on GSM networks; most Verizon customers do not). Once again, you
need an unlocked 3G phone that supports the 2100 band. Calls cost
$2.49/minute; incoming SMS is $0.05/message.
This may be a good choice if you don't intend to use your phone much
and/or want to be able to receive an emergency call. However, at
$2.49/minute call costs quickly add up.
It is no longer possible for non-resident foreigners to get prepay
accounts or to sign a contract for a new monthly account from the
companies in Japan. Doing either requires domestic Japanese
identification which for a foreigner would be a passport plus a resident
foreigner's alien registration card (tourist cards aren't good enough).
Of course, nothing stops you from having a friend in Japan get a phone and
service for you. Of course, if any question comes up about your use, your
friend is in trouble. Anyway, if you have a friend who trusts you enough
to register the phone in his/her name, prepay service is far cheaper than
renting.
Yet another choice is to rent from Verizon in the US. Verizon will rent
Japanese 2G (not 3G) phones, albeit at a higher price for rental and usage
than the Japanese rental companies charge.
Yet another choice is to buy a Japanese 2G phone plus monthly service in
Japan from Verizon. Once again, this is 2G, not 3G, and is quite a bit
more expensive than the same service in Japan. But it is available.
Technically, Japanese law just requires verifiable ID and traceable
financial ties. So a valid foreign passport and a credit card are legally
good enough (that is how Verizon and the rental companies in Japan can
provide service). Unfortunately, the mobile phone companies in Japan
don't want to be bothered, hence the "no non-resident foreigners" rule
for prepays...
For just two weeks, I would advise renting.
-- Mark --
http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.