You make several good points. First of all, being FT, there's certainly nothing wrong with sharing tips on how to optimize out to infinity. I just wanted to add to the thread to benefit those that might wander into it for Japan forex advice and not realize that that's what we're doing here.

To address your second point, let me add a tip: withdraw from the ATM more yen than you think you'll need. Assuming that you have a postpaid hotel room on your last night, take any unspent cash and pay down the hotel bill, putting only the remaining balance on your credit card. This allows you to leave the country with no unspent cash, and without having to pay forex to change it back.