Yesterday I attempted to buy some beer for 450 yen. I handed them a 1000 yen bill (about $10), and they began passing it through the staff in much the same way people back home do when you hand them a $2 bill.
Eventually, after examining the bill, it was returned to me. They explained that the bill was an antique, and that it was probably worth more than the face value. I gave them another, newer, bill which they accepted.
Here is a photo of the bill (top), and its modern version (bottom).