Free Wi-Fi in Tokyo

It’s hard to find good Wi-Fi access in Japan.
Why? Please read this.
http://www.japantimes.co.jp/text/nc20120418aa.html
Simple answer is we don’t need it and we think we should pay for that.
If you pay, you can find Wi-Fi everywhere.

However, there are some companies providing free Wi-Fi these days.
The list has only major ones.

Seven Eleven shops
Need registration.
It seems much easier to resister it at the shops.
Just connect their Wi-Fi network in a shop and follow instruction.

JR EAST

I will add links when I find good ones.