There's also the issue of people going to Japan to buy out several properties to then rent them out.
I do have the impression Tokyo is getting similar dynamics to the rest of the world on this front: builders don't care where the money is coming from and so if money from outside the country can get buildings built they're happy.
A friend of mine moved into a sold-out Yokohama tower mansion recently... and despite the bike and car parking being fully booked even more than 6 months in it was _quite_ empty. I have a feeling a lot of people are buying into the market expecting to get easy rental money and not really seeing it.
the chinese government owns all land and all banks. they snap their fingers and you have nothing.
you put it into japanese, usa, canadian housing, etc. etc. under a company flagged in bermuda and you're covered.
As for regulation costs, airbnbs are notorious for not adhering to regulations. Depends on how well Japan is able to police it.