You know, it's a loaded question. If I had to answer it, I would say that people are defined by their experiences no matter where you go.
Last week, for instance, I met a young lady at a bar. She was born in Japan to Korean parents; her name is Lee. After I made some comments about wanting to "sauce her bulgogi," one of my fellow American friends pointed out that she wasn't all that Korean. Meanwhile, there are all these foreign sumo wrestlers: Asashoryu, who's from Mongolia, recently got pissed at a Korean reporter and called him a "kimchi bastard" in the middle of a press conference. If I didn't know that Asashoryu was Mongolian, I would have assumed he was Japanese (he even disses Koreans perfectly); hell, even the European sumo wrestlers look Japanese to me.
But what is Japanese to a Japanese person?
Well, me, I'm five signatures and a hundred bucks away from having an Irish passport in my pocket. But I've lived in the US most of my life, and if I suddenly decided to exercise my right of return and move to Dublin, people would probably think of me as "the Yank upstairs."
It could be worse. I could be like the poor lawyer in the back of our office. He's Japanese by birth and upbringing, but he lived and worked in New York for a long time, and somehow forgot how to be Japanese without really learning how to be American. Now, he wanders around alone, reading The Japan Times and speaking a weird blend of Japanese and English words that "real" Japanese people wouldn't use.
In Tokyo, you see people from all over. There's a Bengali guy working at the Wendy's by my school, there are Korean and Chinese girls who work the curry and sushi joints near where I live, and they all speak Japanese and seem to function pretty normally in this city.
I think Japan will claim them, if it wants to. I knew about Softbank's Masayoshi Son for years before reading that he was actually Korean. I didn't know about Yomiuri Giants manager Sadaharu Oh being Taiwanese until someone pointed it out during the World Baseball Classic a few weeks ago. Then I said "Holy shit, how do you ever know?"
Maybe there's a future Japan where me, the Irish-looking kid, can be Japanese too. I might change my name (to something badass, like Daiji Masamune), but I don't think I can change the hair color.
It's true that foreigners have a lot of novelty value in this country. The presumption of not speaking Japanese is wearing off a bit: I imagine that the "gaijin talents" on television help with that. But the reality is that many foreigners in Japan don't speak the language, at least not with any level of competency, and that's what people are prepared to deal with, especially if you go out in the sticks where people will just assume you're a lost tourist.
Now, what identity do Japanese people ascribe to themselves? That's still a loaded question, because it's hard to say what makes someone Japanese. Upbringing and lineage put together, I guess.
Anyway, I was talking politics with this Korean Japanese Lee girl, and we were debating the merits of the various idiots who are on the slate to follow Koizumi as prime minister, and she said "How do you know about this stuff?" and I knew what she was really saying is "Why are you infringing upon the sphere of knowledge reserved for Japanese people?" and I wanted to say "I should ask you the same damn question" but I wasn't sure whether she would still let me kiss her after that so I just had to explain that I'm a genius. Even though I'm not.
Notice that I still haven't answered the question. Actually, I'm not the person to be answering this question. I've been in Japan, whether in body or in spirit, way too long. Too much has just become normal. Short skirts? Don't bat an eyelash. $100 minimum withdrawal at the ATM? Bring it on! Sea urchin? Yum! But if I talk about these things with my parents in South fucking Carolina, they think I'm on Mars or something.
In the end, there is no answer. Make up your own; that's all that counts. If you want my input, I'll be in the corner, eating the sea urchin. But if you really want to know, you should just come here.