I've visited Japan but I have never worked there or spent any sort of extended period of time there such as a year or more. I also had a male relative that lived there for several years.
I will say this though, through my own experience with Asian women, of the three major Asian countries (China, Korea, Japan) Japanese culture is fiercely loyal and patriotic. Not to say that Chinese and Korean culture are disparaging of their race, not at all, just that I find Chinese or Korean women slightly less xenophobic than the Japanese are. Having a couple of bombs dropped on their country might have something to do with that.
Japanese women are either open to western culture or they are not. Once they're decided on their outlook, its extremely difficult to change it. I've dated Japanese women (here in North America) that are already set on returning to Japan and that a Japanese man will be their mate once the time comes. They will still be attentive, curious and polite while out with you but intimacy and sex are not on the table. If you pick up on this quickly, you can save yourself a world of frustration. As a man, you'll feel you're doing everything correctly and that you're getting the appropriate 'feedback' (she holds your arm, her body language is geared towards yours, she even kisses you on the lips) meanwhile, in her mind, she's just being polite and respectful of your attention towards her. Remember that she comes from a male dominated society but sex and intimacy are not even on her radar. Don't try to 'seduce' her or change her mind, just move on if its not working for you. Ignoring her doesn't work the same way as it does on western women (where they now want you since you're not 'attainable' any more) she'll just disappear.
Then there are the Japanese women open to western culture and men. They're actually openly seeking a connection since they've decided that they want more to life than Japanese culture has to offer. This can happen both in and out of Japan. There are floodgates of thoughts and emotion here just waiting to be released. The frustration of restrictions and expectations from Japanese family structure, culture and work ethic that they find overwhelming. The fear of being in a job that you're expected to be at until retirement feels like a prison sentence to them. Mainly, the lack of warmth and romanticism lacking in Japanese men. I've given flowers to many Japanese women who have burst into tears at receiving them. "This is the first time I've gotten flowers" or "I've been dreaming of this moment all my life". The vast majority of Japanese men aren't up to romantic gestures leaving the door open for western men to seize the moment, if its a Japanese woman that you desire. Don't rush it though, slow and easy to gain her trust but it doesn't take long.
Once the two of you are romantically involved then anything goes in regards to sex. Keep in mind that Japanese culture is very polite and respectful but it is also free of the stigma of Christianity and its myriad of religions where sex is looked upon as 'shameful' or 'dirty' outside of marriage. Sex will be seen as more fun and exciting from a culture that doesn't apply a shameful stigma to it. It is not in a Japanese woman's psyche to deny her man of sex. She will never be the one to initiate it as that is much too forward but she's ready. willing and able 24/7 for you. She will take an enormous amount of pride in how well she can satisfy you and everything is on the table, no matter how outrageous, she'll be game to try. You might even be surprised as to how far her curiosity extends. Japanese women are fantastic sexual partners.
This outlook comes from my own experience with Japanese women. It doesn't mean that only Japanese women fit this framework, Korean or Chinese women could just as well.
I shared my experiences due to the title of the thread. Hope it brought some insight.
) Maybe that's why it's easy to pick up women, LOL! It's actually kind of funny and sad at the same time - because you will see people who would never act like they do at home - going super-douchy and getting away with it in Tokyo. I've seen the same thing in Singapore too. So Westerners can generally get away with being a total idiot and still get lucky with somebody simply because they're a Westerner. 
