It's hard to imagine how many people over the years have done poorly starting with the story "Japan is cheap and you can make a lot of money buying now before it gets fully valued again".
The problem is, it's generally cheaper than other stock markets for a reason, and most declarations that those reasons are no longer valid have not panned out. Maybe it really is different this time, maybe it isn't.
The spectacular level level of corruption and low level of fiduciary responsibility among top managers is depressing. You might be buying a claim on the future earnings cheaply, but you probably won't receive them.

From time to time in the past I have made bullish noises about investing in Japan when it has been REALLY cheap, on the theory that even if it reverts to its own normal valuation level you'd do fine.
e.g., this post in Feb 2010 which for humorous reasons called for a rise of 76.1% in 4.7 years.
http://www.datahelper.com/mi/search.phtml?nofool=y...
In the end it took almost exactly five years to hit that target, a return of 12.4%/year plus dividends measured in yen. But things aren't as cheap now as they were then, and I personally don't think the business prospects have improved that much.

I think Mr Buffett's play is fine. He has bought a slate as a semi-macro bet on their future aggregate profitability, he bought in at a very attractive level, and the financing and currency hedge cost less than the ongoing yield. But I don't feel tempted to play along.

Jim