You'll see that you can catch a surprizing number of wifi signals, wherever you are. (5 to 10, in an usual street). 90% of them are private and closed, 10% are open.. but usually they wont work. However, by wandering around 10 minutes, you'll probably be able to catch something from a coffee shop or some fellow japanese network.

That's not so reliable, though... so you can find some commercial networks. One of them is run by NTT, i guess, and can be found in public places, some hotels and restaurants chains. Check hotspot.ne.jp. The places are the local brand of burgers "MOS BURGER". Usually quiet enough and burgers are very good.

In these places, the SSID is "033" (or is it 0033)?. To access it, you need an ID and a password. What you have to do is to go to a "familiy mart" covenience store, spot the small touch screen machine that deliver services (ot the ATM!), and find the icon about wifi services.. Then you chose HOTSPOT... one day for 500 yen... and the machine will print a little something that you have to give to the cashier... He will make you pay the 500 yen and give you the paper with your ID.

Sound difficult but, actually,it's very easy and takes about 20 scds.


Also check these ones.. cafes and hotels, mostly.
http://www.freespot.com/users/map_e.html