Tohoku area pass and on line reservation

Hi,
I am quite experienced with rail passes but thing have changed a bit in the last couple years. I have noticed that on the Jr-East website (https://www.eki-net.com/en/jreast-train-reservation/Top/Index?) there's an option that apparently lets pass holders reserve seats on trains, for instance with a Tohoku area pass. Even after reading the faqs and the explanation of the reservation process, is still unclear to me if this website lets you book in advance from your country before having actually exchanged the voucher for the pass once you are in Japan.
Can someone please clarify this?

thank you!

It is quite complicated, indeed!

Yes, you can use the system to make seat reservations before coming to Japan. And then you can pick them up at a ticket office in Eastern Japan by showing a) your pass and b) your pick-up code or the credit card you used for the purchase.

If you purchased your pass through the official JR East website, then you have the additional option to pick up your seat reservations at selected ticket machines by providing a) pass and b) your QR code or pick-up code or the credit card you used to purchase the pass.

It is explained here:
https://www.eki-net.com/top/tr/guide/receive/

voucher is not a pass, ticket.

Yes.

In 2022, I have been able to make seats reservations before exchanging the voucher (bought through a 3rd party, because JR east wouldn't accept my credit card). That was with the Tohoku area pass.