ChrisLi -- Thank you for posting this. I wouldn't have known about this service otherwise.

The 30 day SIM is available only online through their b-Market site. I believe the other longer term SIMs are available at many retailers. After ordering the SIM, it was delivered the next day by Sagawa.

The SIM itself is branded as NTT Docomo FOMA. It has a label with the phone number of the SIM, and a toll-free phone number for activation. Guidance in English through the automated activation system is available. For some reason you must call from a mobile phone, but not the device being used with the SIM since you cannot make voice calls. When I first tried from a land line I got a recording instructing me to call from a mobile phone. Activation requires you to input the phone number of the SIM, and the system tells you that the device will be active within 5 minutes.

I set the APN, username and passwords as indicated in the instructions. The instructions themselves are in Japanese, but it's easy enough to see the APN information.

I did some speed tests using speedtest.net to a server in the Tokyo area. Download and upload speeds are consistent at 300kbps. Latency varied from 150ms to 800+ ms. Most of the time they were in the 150ms-200ms range.

I've been using the SIM for less than a day, but so far it looks pretty good. This will allow me to use my unlocked T-Mobile HTC HD2 for everything I need but voice calls. Google maps is working fine, and I'm able to send and receive email messages. I am also able to use the HD2's hotspot mode to be a wifi router, and I'm able to connect via wifi from my laptop. It's not as fast as the UQ Wimax service that I'm also have, but it's available in many more places. I will be camping at Asagiri Kogen for 8 days in August for the 15th Nippon Jamboree, and based on coverage maps, I won't be able to get UQ Wimax there, but I should be able to get FOMA service.