The distance is 536 miles, at a cost of $202 in the Green Car. The round trip is, thus, $404. A Green Card one-week Japan Rail Pass costs $345. I plan to use this pass to get from Shin-Hakodate-Hokuto to Sapporo and back, at a cost of $158. Note that it takes only about four hours to get from Tokyo to Sqhin-Hakodate-Hokuto, but around 3.5 hours from this station to Sapporo, even though it is only 181 miles away. I will still be going to Sendai, Nagoya, Matsumoto and other sites, so it you have plans to see Japan, buy a rail pass.
Further, I thought, heck, why not also take side trips to Bangkok and Seoul. So follow me around the Orient for the next 18 days.