Seishun 18 kippu from Hakodate to Kansai

I managed to trace a map of a route from Hakodate to Kansai using the Seishun 18 kippu while stopping in Niigata on the first night. I was wondering if anyone has ever tried. Is it a hassle to transfer trains? any main difficulties during the transfer? Whether any trains cost extra because they were not included in the seishun 18 deal.

Is it a hassle to transfer trains?

Usually the transfers are easy. But if you don't prepare well or don't speak and read Japanese, some transfers might be slightly challenging, especially on some of the more rural stations where English signs could be scarce. In that case, just ask the station staff or fellow travelers.

Whether any trains cost extra because they were not included in the seishun 18 deal.

Not if you plan your trip well to include only local and rapid JR trains (and a limited express train between Kikonai and Kanita). The trip from Hakodate to Kansai can be done with the Seishun 18 Kippu only.

According to my research, it is possible to travel from Hakodate to Niigata in a single day if you leave Hakodate at 6:53 and arrive in Niigata at 21:03.

oh i see. I wasn't aware that the limited express train between hokkaido and honshu was included in the ticket. Thank you for your help!