The guidebooks all tell you to rent a car if you want to explore on the north island Hokkaidō.
The guidebooks are right.
Trains run all over the island, but actually connecting from one to the next on the local lines is tricky.
It IS easy, however, to get to the northern tip of the country, Wakkanai (稚内市).
You CAN see Russia from here, Sarah. (The island of Sakhalin.) But not when it’s grey and miserable. And it’s always grey and miserable in Wakkanai from what I’ve seen. And windy. And cold.
The further you get from Tokyo, the less English. Not even train stations have much English. But this town is bilingual — Japanese and Russian. There is a ferry from here to the mainland.
Without help I wandered the town at night in the drizzle unable to find any of the 3 hostels — all had closed for the winter, as it turned out.
I ended up in less cheap business accommodation, Petit Hotel Joy Wakkanai. Hot shower, fast internet and traditional Japanese breakfast.

… just about to go check the feasibility of a day trip to some nearby islands, for hiking.
That will be a disaster — if I go — guaranteed.

The one thing I never warmed up to during my year in Japan was the breakfast. Yuck. Stay safe up there – and warm!