There is reserved seating on the Limited Express, Express, Rapid Airport, and Sightseeing trains.
Present your Hokkaido Rail Pass at the station ticket counter and state the date, train name and zone you wish to use and a reserved seat ticket will be issued at no extra charge.
It is possible for you to purchase reserved seat tickets in advance using JR-EAST Train Reservation. （※Bookings cannot be made for sightseeing trains or special trains.）Please refer to the following links.
When tickets are inspected aboard the train be sure to present both your rail pass and reserved seat ticket to the conductor.