I think I'm amongst the younger folk in this forum but in the UK when I was growing up, there weren't really any areas concentrated in Asians asides from Indians. There were in fact, hardly any from SE Asian or Far Eastern descent. Kinda made it weird in ways growing around around all of this, knowing you're different to everyone else but I clung onto it for dear life. I am happy that things turned out the way it has in the present, with lots of communities of different races existing in most places around the western world. It's helped to stamp out most racism, which is what I was subjected to a little when growing up.
I grew up here in the UK and asides from family friends, I knew of no other Asian asides from Indians. I remember if I walked down the street I would get stared at, and just as moreso by other SE Asians who might have been just as surprised as I was to see the other. I was so westernized when growing up because asides from my family-life there was no contact or reminder that I was Asian.
It wasn't till a few years ago that the Asian inside of me kicked into gear and although I love western culture and am glad I grew up here, I will always love Asian culture the best. I know a lot of my parent's friend's sons and daughters and similar Asians who grew up here and are my age who have said that they feel really westernized. Most of them do not even really speak their "native" language anymore. Sometimes I think about it and find it really strange, but you really have to find something you want to hang onto for it to work. I think in many ways I think like an English person but my sensibilities feel Asian. I guess it's about filtering out the things that don't matter to you and getting the best of both worlds.
I have come across a lot of British-Asians and American-Asians who are quick to denounce their heritage. If I ask them of their origins they reply "England" or "American" in the perfect appropriate accent. They sometimes seem embarassed when I reiterate "origins" and tell them they do not look English/American. I see this as possibly the ultimate extreme of being Westernized... where you no longer even think of yourself as an Asian!
The comment about your half Japanese friend is interesting, Moyashi. The "half-breeds" tend to get a lot of stick from natives but me, I give just as much attention and respect to them since I know it must be harder for them to retain their identity.
I agree with Moyashi. Try not to lose sight of who you are while you are trying to find yourself
Good luck in finding your happy place, wherever it may be...