Do post offices in japan offer US cash exchange service?

Question:

I know so far that post offices let you take out yen from debit/visa cards using ATM machine, my question is whether they also exchange liquid cash for yen. I am traveling with US dollar cash, do they accept it? Or should I exchange all my money at the airport, however I ve heard that narita airport takes away a big chunk of commission

Answer:

Yes, but not all - in fact only the largest of them do. But all of them have ATMs that you can use and they have menus in English. Actually you will get a much better exchange rate using your ATM.
If you want to exchange dollars for yen, the larger post office is a good place to do so. You don't have to use a bank at all if you want. The Narita Airport Post Office is on the 2nd floor, you can get some yen with your card, and just go to any large post office when you get to your destination.