Confuse about jr limited express and which train do i need to make reservation?

Hi, i'm a bit confused about is this train covered by jr pass or not?

1. Jr yosan line limited express

2. Jr ou line limited express

And which train do i need to make reservation? As far as i know is train from tokyo station to sapporo station .. can you tell me what's more routes that i need to make a reservation? (I mean, if i don't make a reservation first, i won't be able to ride the train because all seats are reserved seat, no unreserved seat)

Thank you before