The information has published at https://montreuxjazzfestival.jp/4
In addition, priority sales might be offered for SEATBELTS supporters.
It will be announced soon.
If you receive an email from office@seatbelts.live, it would be https://seatbelts.live/getting-ticket-en/
All times are JST.
You should try to convert it to your home country’s time if necessary.
You can buy your ticket at Pia’s site. The URL is not published now.
If you receive our priority offer mail, you can buy the ticket with the procedure on it and get your tickets on the day of the concert at the entrance.
If you don’t receive our priority mail, and have a credit card issued in Japan, you can apply the ticket via PIA’s site.
Unfortunately, if you don’t have any credit card issued in Japan, I’m sorry, I don’t have any idea now.
I will suggest PIA that they should have a channel for foreingers.
PIA has an English FAQ.
The following brands of credit cards seem to be available.
VISA and MasterCard and JCB and DinersClub and AMEX.