[throwaway197812]

Can't speak from personal insight, but I recommend checking out the Tokyo Llama channel on Youtube: https://www.youtube.com/channel/UCBQ3TEq5SrUuTJuMl1S_4ig (also linked elsewhere in the thread) to see what the experience of buying and fixing up an akiya is really like.

In their case, they had fairly specific location requirements and thus restricted themselves to Ibaraki prefecture. So fairly close to Tokyo (1 hour train ride I believe?), but they paid much more than $500 -- more like $20-30k if I recall. Once you go through the bureaucracy of buying it (making sure it doesn't have a tax lien, etc.), you're basically faced with a falling-down hoarder house that you have to clean out and likely tear down and rebuild completely. Theirs was also a quite large lot and a nice traditional Japanese farmhouse called a minka or kominka (https://en.wikipedia.org/wiki/Minka). So, not typical of these $500 houses -- those are probably going to be further out from the cities, much smaller lots, and complete teardowns. But do expect to invest significant time and money to get it to a habitable state. And you'll likely need to speak much more than tourist Japanese to deal with the local bureaucracy and builders.

But if you're willing to put in the effort, and you do like the quiet Japanese country life as a getaway, it could well be a good investment. This is pretty much my plan for (semi-)retirement in a few years.