I am going to Tokyo this Xmas holiday. When i look for information about that, I found a good choice for you, if you need to use internet in Japan.
http://en.ivideo.com.tw/jp/top.html Because this is my first to Japan, I would need to check the google map, this is a good idea that I can use in Japan. And now I can change my post on blog for free use. I will be in Asakusa during Xmas, if you need to get on line, please contact me. Because I can share the internet with you, too.