Interesting read because I'm quite frankly, the opposite.
Brief background.
I was born in Japan (Born in Hiroshima, but my 'home town in Japan' is Kochi, in the Shikoku Island) and came to Australia when I was 6 (I'm 24 now), and have pretty much lived my life here (Perth). I don't go back often (in 18 years i've been in Oz i've gone back 5 times, no more than 3 months each time). My first language is English and my speaking, understanding, reading and writing of Japanese is about a level of an 8 to 10 year old.
The relevant posts are all pretty informative and i wont disagree with any of them. Even the racist bit, I initially thought wrong of it but now I understand the subtle racism factor. It's difficult for me when I go back because they think I'm Japanese and naturally accept that I speak, understand, read, write, even LOOK like a normal Japanese person where within me I KNOW I'm more Aussie than anything. So when they realise I'm not as Japanese as they made me out to be, I'm treated like any other foreigner. :\
I haven't stayed in Japan long enough to see the effects after say, 6+ months or even years, but that might be different because I might be able to understand the culture / social aspects / pick up my own language quicker. So after a period of time they might accept me for a proper Japanese person again. Who knows.
I've stayed in Australia long enough to accept the lifestyle, culture, values, etc to the point where I think that living in Japan probably isn't for me, even though my dad has lectured me countless times with the ol' 'don't forget your Japanese' speech.
I've met a few foreigners in Japan and its fascinating hearing their stories and what made them come to Japan, what's keeping them there, what they like, etc. I think that's because I'm pretty much a foreigner myself. In my own country. If you get what I mean.
Sorry, haven't really stayed on topic, having more of a ramble than anything. I just wonder what'll motivate me to actually go back to Japan one day and stay there for an extended period of time.