It’s hard to find good Wi-Fi access in Japan.
Why? Please read this.
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
It seems much easier to resister it at the shops.
Just connect their Wi-Fi network in a shop and follow instruction.
Ok, they don’t have English website.
Don’t need registration for this one.
I will add links when I find good ones.