Train seats reservation JR Pass EO holders

Hello! I have a question which I can't seem to find info on the website. I am holding an exchange order for a 7-Day JR Nationwide Pass and will land in Haneda on 22 Dec. I registered an online account with JR East, hoping to do seat reservation on eki-net for Joetsu & Hokuriku Lines. However it appears that JR Nationwide Pass is not on the list of passes available for selection, unless I select one of the applicable JR East Passes (eg JR East Pass). It allows me to proceed with seat reservation but I'm worried I might have problem with ticket collection as the specified pass is incorrect.

Does it mean that I won't be able to reserve seats online before arriving in Japan? I tried Smart-EX website as well for Tokyo-Kyoto, and no luck too. Please assist to clarify. Many thanks.

I am afraid you won't be able to make seat reservations until your arrival in Japan. But that should not be a big problem except possibly December 29-31 and January 2-4, when the New Year rush takes place.

The JR East online reservation system does not seem to support seat reservations for the Japan Rail Pass.

Thank you very much for your quick response Uji. We have been reading about overtourism in Japan right now plus I'm travelling during the ski season on weekends so pretty worried about travel dates can't go as planned. But guess there's nothing I could do now. Thanks again.

to Uji,
OP is a voucher holder. so, I think he/she can't make seat reservation online.

even after he/she arrives in Japan.
I think he/she can reserve the seat only at stations.

Thank you Ken. Yes I'd go to Ticket office to exchange and make seat reservation.

even after he/she arrives in Japan.
I think he/she can reserve the seat only at stations.

That's right. Reservations can be made at ticket offices and selected ticket machines once the OP holds the actual pass.