B-mobile is what is known in the industry as a MVNO (Mobile Virtual Network Operator) which, long-story short, means it simply borrow a physical network from a larger mobile operator (in this case NTT DoCoMo).
The company's main product is pre-paid cellular data for users who want to be able to access the internet where ever they go. You can see their English page here, although the product selection is limited to mobile per-paid internet modems. The Japanese page has a much more comprehensive listing of data and data/voice SIMs and modems.
Stand-alone SIM cards are still a nitch market in Japan so there are not a lot of cost effective options to choose from when it comes to voice and data. B-mobile offers a SIM-only voice and data solution for about 3,960 yen a month plus (including approximately 32 minutes of talk time), start-up fees (3,125 yen), and unlimited data. Canceling within a year incurs a 10,500 cancellation fee. So its basically not all that different.
If you sign up for a voice plan SIM card then you will have to verify your identity much like a regular Japanese mobile phone. This generally means you have to have a valid form of Japanese ID.
Data-Only SIMS and Modems
A more practical option for the short-term visitor looking to stay connected is a data only SIM or modem. B-mobile offers English service and activation for their pre-paid data products such as this USB Modem. The Japanese website also offers a plethora of data-only SIMs that work with 3G/4G networks.
These SIMs and modems are ideal for those who want to use their phones or laptops for e-mail and Skype. Since voice calls in Japan are expensive and even the most basic mobile phones have e-mail addresses, you should be able to get by with a data-only SIM or modem.
The company's website lists several retailers that carry pre-paid SIM and modem products products. In addition, Amazon.co.jp also has a hefty selection.
If you are looking for more great info about getting a traditional mobile phone, then check our great Japanese mobile phone super series below.
Other posts in this series:
Part #1: The Basics
Part #2: Important Paperwork