Second: It is often said that 90% of the world doesn't know there is a correct way to play poker and of the 10% that knows, only 1% actually understand what it is. Well in Japan most may have little knowledge of the game but all of those that play understand the game very well, and are always a threat at the table. In eight years and after meeting hundreds of players, I have only met one that might be considered a "donk." The rest, all, played a good solid game of poker. In a recent five table tournament, my starting table had three players that made final tables at the WSOP. A good rule of thumb is to consider any Japanese player you encounter as competent until their play indicates otherwise.
Finally: Most westerners consider all Asian players loose, gamblers, and action players. In my experience that is true of Vietnamese, Chinese, Thais, and to some extent Koreans. It won't take long sitting at a table of all Japanese players for you to reevaluate grouping the Japanese poker players with the rest. Luck is not in their vocabulary. Their favorite hand is pocket Aces, not 8-6 suited. When they play, they have good cards, and understand the proper odds required for any marginal play they might make. If they have a weakness it might be to play a little Weak-Tight, but they are not above a little larceny and understand the value of solid aggressive play with some marginal cards.
Most of you will never be the only gai-jin sitting at a table full of Japanese, but be warned it is significantly more dangerous to your bankroll, than sitting at a table full of "locals" in Las Vegas. When poker finally becomes mainstream in Japan it will be bigger than Golf, and I expect our EV will suffer with the increased number of competent poker players.