That's illegal in most developed countries

To be fair, housing alone is a low bar. I'm sure plenty of homeless people could technically afford somewhere to live, but don't find any of their available options worth it for whatever reason. Wonder if there have been any surveys on this.

> Housing is already affordable in Japan.

You must not be living in Japan then

Housing can always use becoming more affordable. Perfectly affordable housing is when an ordinary worker without a university degree can buy a decent single-bedroom apartment in just some years of saving (which sounds totally unrealistic so there always is room to improve). I've read it even is hard to rent a decent apartment in Japan because they always require huge deposits only the rich can afford easily.

There are homeless people, at least some of them not particularly happy about being homeless, also 30+ yr. old people having to live with their parents - means housing is not affordable enough.