There are a surprising number of abandoned buildings in Tokyo. On a recent tour we were told that this happens when something “bad” happens in a building. People find out and do not want to live there.
In this case, something bad happened about 10 years ago … and no one has lived there since, except the every expanding vines.
Michael Weening: a few pictures 
Vertical gardens are in vogue at the moment. This would blend in.
If you didn’t want to see out the windows. 🙂