For what it's worth, I routinely have difficulty with using Chase Sapphire in Japan. It is definitely a compatibility problem with some card readers. I'd say that it works about 95% of the time, but the other 5% it doesn't matter how many different ways they try to swipe it. Most recently, I ran into a vendor who had 3 different card readers (no idea why) and it didn't work in their preferred reader, but did work in one of their other ones. (All were Panasonic readers.)