I finally decided a few weeks ago to try OCN’s eMobile service. For ¥700/month you get a 3G internet connection you can use anywhere (right now I’m in a train going to Akihabara).
While in Japan 3G Internet service is usually unlimited, it gets less or more expensive depending on how you use the service. For the eMobile service via OCN it starts at ¥700/month if use it only a bit, up to ~¥3,600/month if you transmit over ~32,000 packets.
The specific part is once you reach ~32,000 packets, you don’t pay more for whatever else you transmit, and ¥3,600/month is still cheaper than the usual service in France, and the service has a far better quality.
And a final point: requesting eMobile from the OCN website is as easy as logging in, clicking “contract informations”, choosing the “EM service” and confirming the shipping address.
Login and password are the same, ATM is “ocn” and you get an OCN IP with ability to connect to port 25, run a webserver, etc…
