A fascinating article from The New York Times I found by chance just now: "A Sprawl of Ghost Homes in Aging Tokyo Suburbs." By Jonathan Soble, 23 August 2015.
"[A]fter decades in which it struggled with overcrowding, Japan is confronting the opposite problem: When a society shrinks, what should be done with the buildings it no longer needs? ... 'Tokyo could end up being surrounded by Detroits,' said Tomohiko Makino, a real estate expert who has studied the vacant-house phenomenon. Once limited mostly to remote rural communities, it is now spreading through regional cities and the suburbs of major metropolises. Even in the bustling capital, the ratio of unoccupied houses is rising."