I got a coupon code "Fuji" from the site myjapanphone.com, Blackberry rental company
The code offer 50% discount on renting a b.berry (unlimited data!!). Their berry model is 8707, which can work in States, Europe, Far East, including Japan and Korea.
I'm planning to rent one for my trip, they're the one I found the most cost-effecient.
Any other recommendation?