I just had my local bank decline paying the registration fee for an upcoming conference in Osaka. I then switched to another card, and the card issuer sent both text and e-mail messages asking if the charge was legit. When I responded that it was, the charge went through.

Card issuers tend to question anything that is outside the cardholder's normal spending habits, especially foreign transactions. Some banks will just decline the charge and contact you days later. Others (the efficient ones) will immediately send an e-mail or text message. Others will allow foreign charges if you warn them ahead of time.

So try another card.