Local searching for foreign currency

I'm planning a trip to Japan in the spring. I'm looking for anyone who has been before, 1 so I can pick your brain, and 2 if anyone came home with a bunch of currency that's now just sitting and you can't easily exchange. I plan to go to the bank for the bulk of course, but willing to do 156 yen to $1 if you just have a bunch of coins laying around your like to get rid of!