There are homeless people in Japan. You'll see them sitting in alcoves by train stations or sleeping under a stack of umbrellas in parks sometimes. The places I've seen them most are in remote locations by rivers, where they'll set up tents or tie tarps to trees to live under. They aren't as ubiquitous as they are in the US though, and I've only seen a homeless person panhandling once in all my years in Japan.
There are lots of homeless in Japan, and people do see them.
Anyone living near Tokyo who has money, clothes, shoes, gas cans, batteries, shelter material, work opportunities etc they wish to pass on - please reply here or email i.am.grozzle at gmail, please. Or ask staff at Lavanderia cafe in Shinjuku ni-chome.
According to a very untrustworthy source (https://en.wikipedia.org/wiki/Homelessness_in_Japan) the numbers of homeless people are somewhat low-ish, if those numbers are anywhere near accurate it may account for the low visibility of the problem.
> Is that why you don't see any homeless in Japan? They just arrest them for vagrancy and house them in jail?
Each time I've been to Japan I've noticed plenty of homeless people. They are really tidy about it, but you'll find encampments in Osaka and Tokyo if you just check out some of the parks.
There are limited public places to "sit" in Tokyo/and other cities too, for example, this is increasingly common part of civic design, to encourage either "moving on", or "taking refuge" in shops/cafes > ie. spending.
Is that why you don't see any homeless in Japan? They just arrest them for vagrancy and house them in jail?