There is a fee for Mastercard/Cirrus on 7/11 machines, I believe it's Y2100. Visa/Plus carry no charge. And yes, you will get the same pricing at any 7/11 ATM in Japan.

If you find a bank ATM that accepts foreign cards, there will be no charge by the Japanese bank for using it, at least I've never encountered one.

Greedily, Citibank charges you the same "foreign ATM" fee for using a Citibank ATM machine outside the U.S. that it does for using any other accepting ATM machine. This charge is relatively recent, I think.