http://news.yahoo.com/news?tmpl=story&u=/afp/20050725/lf_afp/afplifestylejapan_050725144604
Japan will try to stop the building of big shopping centers and hospitals in suburbs in hopes of halting the exodus from city centres before the population begins to shrink, officials said.
A separate study earlier this month by the land ministry said the aging population in itself could help stop suburbanization.
It predicted more people would be drawn into the cities as space became more plentiful, while suburbs would increasingly be domains for the elderly.

Why don't they just build a big fence around the middle of the cities, pass a few laws and say: "now everybody inside here can't leave, report to the local ward office for your breeding instructions." Better not to mess around when tax Yen is at stake. Blinky would like that, keeps the stock pure.