I've also had problems a couple of times in Japan w/the Chase Sapphire. As others have recommended, I always present the back of the card with the numbers showing to help to eliminate some confusion. A few times (Daimaru above Tokyo Station) they gave up after failing to get the card to work and with my limited Japanese, I decided not to belabor the point and handed them a different credit card that was more traditional than the Chase Sapphire.