There are risks you cannot afford to take because, if anything goes wrong, you're out of business. And there are risks that you cannot afford not to take no matter how dangerous, because, if against all probability things turn out well and you're not in there, you're out. In Japan, I'd suggest maintaining a separate account. Make it clear that you treat Japan as a long-range investment. For five years, Japan will not produce income for your shareholders, but then it will, and you'll be ready.
Financial services are a fantastic opportunity there.
The country has none, basically. Whatever financial services are in Japan are offered by foreigners. There are no opportunities in Japan in commercial banking, but that's true of everywhere in the world. Commercial banking is a dying industry. A lot of Japanese businesses will be looking for foreign partners, especially in finance, but perhaps even more so in consumer goods, in production, and in some areas of distribution.