You can get a house within a "reasonable" commuting distance of Tokyo for 50 million yen or so.
Housing as an investment (if that is indeed, what you are looking at), from what I know:
Most houses are a declining asset (a 20 year old house is worthless as a building, generally speaking)
If the land does appreciate, capital gains tax will kill you.
It's been a while since I looked at it, though, so maybe things have changed (I once considered buying a house in Japan).
Sorry for the cut and paste links, but here goes:
At least one person has a different idea on how to purchase a house, though it wouldn't be in the Tokyo area:
Some quick overviews with very general info:
A dated (1988) article on capital costs and taxes: http://www.esri.go.jp/en/archive/dis/abstract/dis44-e.html
Speaking of capital gains taxes (section 5 in the following):
For an explanation of this quote: "The fact is that a house is not an asset with durable value in Japan", then see:
I'll assume, though, that as a real estate developer you know a heck of a lot more than I, or maybe just want a second home, so without further ado here are some real estate sites: