I listened to a show on the radio not long ago, and it reminded me of the Japanese documentary (posted in this thread) of the people sleeping in Cyber Cafes. I believe Lost in Mamboo is the name.
Turns out many individuals living like that, there, are actually running from debt collectors. Often it's due to gambling, and they do love to gamble it up. Drugs are almost unheard of outside of the mob world.
But the debt collectors are said to use tools such as megaphones, lol, to stalk a subject at his/her home, making a sun-up 'til sun-down effort to "coax" the person into paying. If someone doesn't have the money, that person can "disappear" into a scene such as the cafes. They're not broke, obviously, since they're charged a few bucks per day to flop in their little cubicle. It's all anonymous (the Japanese respect the need for that) and it's cash on the barrelhead. Five years of living under the radar, and they can come back in the clear.
The broke Japanese are often older ones, sometimes very old, and were sadly left behind due to a business failure (whether by self, or someone else). Almost 100% male, as women are better seen-to in that society.