Using my US dollars and exchanging them to Japanese yen this summer while 1 dollar being equivalent to 75 yen average. Taking into account that a bottle of coke is 150 yen and a McDonalds meal is around 600 yen to 800 yen, I had to prepare myself to see my money fly away!
If you want to take out money from your BANK OF AMERICA account (I'm not sure for other accounts!), go to your nearby post office and use the ATM!
Convenience stores which are located anywhere in Japan also have ATMs. However for some reason, I could not withdraw cash from those.
Post offices are everywhere in Japan as well so don't you worry!