Sorry I didn't make it clear. The bMobile SIM is extensively discussed in the Japan forum in this thread:

http://www.flyertalk.com/forum/showt...ferrerid=14479

It generates a wifi hotspot (if that is what you want) or makes your phone into a data terminal, but it connects to the internet through DoCoMo 4G LTE wireless service. DoCoMo service exists pretty much everywhere people do in Japan.

On my last trip, my kids used it to send service to a wifi-ony iPad but also to access Google maps on their smart phone (and email etc etc etc). It does everything except voice calls and SMS, but does support Skye.