A bit of a surprise, the discount ticket shop on Higashi bypass, just as you go left onto Kita bypass (Nishi Nihon Chiketto), has foreign currency. I assume they also purchase it. Not sure about the rate, but good to know if you have to quickly get some cash before a trip. The sign says they also have Euro, Chinese Renminbi, and Korean won. So if you have to play uncle or auntie and want to send a christmas card with a $20 bill in it to your niece or nephew, you know where to go!