According to this post, Japanese don’t expect the value of their houses to grow. It seems that they routinely recognize the house and land as separate purchases, and after a few decades the house might have no value at all. The inference is that land value also might not increase, but at least is unlikely to drop much. (Of course the same trends in value occur in the U S, but we tend not to recognize it.)
As a result, empty-nesters in Japan don’t count on funding their retirements by selling their houses. As noted in the comments, this also means that housing in Japan is much more affordable than in North America.
Another post by the same writers observes that vacant land in Japan is subject to very high taxes — six times the rate for land with structures. So landowners are reluctant to demolish worthless houses. The result is over 13% of houses (as of 2013) were vacant, many of them deteriorated and uninhabitable. (This article asserts that Japan had 8.5 million “abandoned homes” in 2018, but provides no source and doesn’t define “abandoned.” This table from the Japan Statistics Bureau reports 8,764,400 vacant dwellings, 14% of Japan’s housing. Most are “for sale” or “for rent.” )
14% seems like a lot, but the equivalent U S rate is 12.2% (according to the press release here which might soon be memory-holed in favor of an update.)