How to go from Aomori to Sapporo using Rail Pass in April

We're planning to travel to Japan late April and want to go to Aomori and Sapporo for the cherry blossoms. We want to travel to Sapporo from Aomori using train but it looks like several of the trains going there will be discontinued. We found that the Hokkaido Shinkansen will start running at end of March but we're not sure if we are able to take it using the pass. Could you please help us on what to do to get to Sapporo from Aomori using the rail pass? Thank you.