Tokyo-Hokkaido

Hi there!

I am making plans to travel from Tokyo to Toya on day 1, and Niseko to Takasaki on day 5. From my own research, it seems like the 6-day JR East-South Hokkaido Rail Pass would be the most economical, but I just want to affirm this assessment with you experts here? :)

Separately, would you know if with the JR East-South Hokkaido Rail Pass, I would still only be able to make seat reservations after I have arrived and exchanged for the pass in Japan? There is a train that I want to book with the pass, but it's so popular that I am sure it would book out as soon as reservation opens a month before. If I can only reserve the seats after I arrive in Japan, maybe I need to plan to purchase the tickets for that train separately.

Thank you for the help! Really appreciate it!!