The bad thing about Japan is that free wifi is hard to come by. You'd expect a country who brought you PS and Wii to have free wifi access everywhere you go! The reality is, even in Tokyo it is difficult to find free wifi spots. Starbucks and certain public access areas can be found but it is a lot of work and not very convenient. To make matters worse, the farther away from the towns you go the harder it gets to find free wifi.
So I have been shopping around for a reliable data only service. It seems like most service providers only focus on people who need coverage for a few weeks tops. But I will need it for two and a half months. They have prepaid SIM card plans for 30 days, but my phone is locked and I don't want to buy another unlocked phone. Prepaid phones are pricey. The mobile wifi units seem to be the best option for data only service since I don't really need phone service.
So far, the best plan I have found is through "Let's Internet JP." They have long term wifi rentals from 4250 yen/30 days...but minimum use is for 120 days. So the final sum comes out to 17000 yen for unlimited data only usage for 4 months. This seems to be the best deal so far...
In case you are wondering, that is not me in the picture nor do I know her...I just found it off of Microsoft PowerPoint clip art LOL.