[Sangetsu]

More than likely it is as Nyororin said, they are probably sending you an application to manage your account online.

If I were you, I would try to find some way to get some money to deposit into your account so you can cover your payment. You do not want to risk your credit rating, it's hard enough for foreigners to establish credit in Japan.

If there is no possibility of deferring the payment or deposing additional funds to cover it, you should probably apply for another credit card now, before any derogatory information gets reported. And try to get a regular revolving account rather than a charge account.