I have no idea; AA doesn't use a GSA in Japan as they have their own offices there. Because it's such a specialty product they'd probably kick it back to the US RTW desk and wherever AA now does its pricing (RIP Dublin office). Whether you could fax a credit card image to some Japanese office... no idea. Phone the RTW desk and ask them.

As for how long they'll hold the res, I suspect only for a couple of days, maybe a week, but things have been tightening quite a lot on such things in recent years. Again, a phone/Skype call will help answer this.