OSAKA -- In the back streets of Osaka's Nishinari district, thousands of elderly men loiter, stopping only to eat at a 100 yen ramen stand or join in a yakuza-run floating craps game.

They have nowhere to go. Many sit on the street corners in a drunken stupor, muttering to themselves, while others quietly pass the time smoking and drinking beer.

The district has long been home to Japan's largest concentration of homeless people, and it is a society within a society, with unwritten rules and a code of conduct. Volunteer social workers in the area estimate there are about 10,000 homeless people in Osaka, of which about 80 percent live in and around Nishinari.