Osaka is in Western Japan. so you would need a converter if you bring it from the States. I would wait and get the laptop there. Having the Japanese keyboard (which, I should say is QWERTY layout, with kana as well) is so much nicer than trying to type in romanji. Good deals abound, especially in the big cities. Check out these links for English support, software and systems.
www.mcljapan.com
www.users-side.co.jp
Most of these guys offer dual-boot systems, but it's really not necessary. PM me if you need more info.