Originally Posted by
rustykettel
ETA: I've booked domestic flights through JAL's Japanese site and had no issues as a visitor. I'm not sure about the new system, but the old one would allow you to make a booking without payment and then it will cancel if you don't enter payment details within the timeframe (I think it was 48 hours or something like that for my particular fare). That's about the only thing I can think of to look out for.
I can only second that. No problem whatsoever using the Japan region site for domestic bookings even though you live outside Japan. It is not a problem using a non Japanese credit card either. The part that can be surprising is that booking and payment in the old system is separated, and you need to go back to your booking to process the payment. Don't know if that is planned to change in the new flow.