if you’re coming to japan for a couple of weeks or months and want to use your phone, but don’t want to hire one or pay outrageous roaming fees for data then bmobile is for you.
bmobile offer sim cards that connect to the ntt docomo network and give unlimited data connection, albeit at slightly slower data transfer rates than is possible with the big players.
however, the cost is amazing: unlimited data packets in three plans: 1 month (about Y3500), 6 months (Y30000) or 1 year (Y60000).
They also have sims for iphones allowing you to use an import phone without using softbank (who are shit).
bmobile have also launched a talking sim plan which offers voice, the ability to transfer your japanese phone number to them and unlimited data for a flat fee of about Y3500 a month (including 25 minutes of voice).
The data only sims are available in many major electrical retailers for over the counter (6 or 12 months only) but you can get the 1 month direct from their website (unfortunately delivery only to japan).
so if you’re coming over to do study, travel for a bit or whatever and want to bring your phone and do mostly data then i can highly recommend bmobile.
list of all bmobile stuff on amazon.co.jp
bmobile online shop (direct order including 1 month data only sim available only from them online – check the boxes at the bottom and click on the left for credit card payments. use google translate if you get stuck!)
have fun.