perhaps it would be interesting to consider the role trends play in this. in contrast, in niseko (another ski town in northern japan) which is very trendy now and undergoing a lot of development, a new condo of 850 square feet goes for north of US $1,000,000

the skiing in niseko is likely better but would also require a flight plus a train ride to reach.

also, just to note, cheap real estate in the japanese countryside is not at all unusual. many towns have implemented various programs/incentives to try and make use of existing/unused housing and attract young people to the countryside.

a number of years ago my wife and i spent a weekend in a tiny town roughly 3 hours drive from tokyo. there was only one restaurant and they obviously knew we weren’t from around there. at some point during the meal they tried to sell us on the idea of relocating there. there were financial offers to help us in renovating one of the neglected/idle properties with additional incentives down the road if we were to have children and enroll them in the local school.

i suppose the demographics make this situation unique to japan and less likely in the US.