JR East-South Hokkaido Rail Pass and Nagano

Hi Daniel San,

I am planning to go to Sapporo with JR East-South Hokkaido Rail Pass but I also want to go to Nagano later.

I notice that -South Hokkaido Rail Pass covers the Shinkansen train to Karuizawa. Do I just need to pay the fare gap between Nagano and Karuizawa when I book the ticket? Or I need to pay the full fare if I leave from Tokyo.

My appreciation.

Cheers, Sonny