I asked myself the same question when I saw exactly 1 homeless person in all of Tokyo.
There has been a global trend to decommission psychiatric hospitals. Japan didn’t follow suit, and today has 10x the beds per capita compared to the US.
This is balanced by the fact that it’s much harder to commit someone against their will in the US.
https://www.borgenmagazine.com/japans-homeless-population/#:....