Additional information for Decay, Japan
Last night’s Japan Times ran an article on vacant lots in Japan. In the article was this.
“It helped that, under Japanese law, these vacant plots were taxed at a higher rate than those with buildings on them. Of course, it’s for this reason that Japan is now seeing a rapid proliferation of abandoned homes, or akiya, as owners opt to let such structures decay rather than have them demolished.”
So we have another and perhaps more important reason for abandoned houses here.

Politicians yet again failing to understand human nature and yet again failing to solve any issues.
https://resources.realestate.co.jp/buy/what-you-should-know-before-buying-a-vacant-house-in-japan/
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You can look at Fixed Asset Tax records, but that doesn’t help when the owner is deceased and isn’t paying anymore. How can you be a buyer when there is no seller? The answer is you can’t, and so the property remains vacant and abandoned.
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I were looking for what exactly constitutes a "vacant plot" and found the above interesting point.
Couldn't find a clear definition of what constitutes a "vacant plot", but it appears to have to do with tax cuts for buildings which requires maintenance of some sort. So converting the plot into a public park or installing a statue would likely not result in lower taxes at the very least.