I've lived seven years in Japan. Even if I were to get Japanese citizenship, I wouldn't identify myself culturally as Japanese (and neither would Japanese think of me as Japanese).

Countries like the US separate cultural identity and citizenship, so having citizenship but still being seen as a foreigner might seem a bit strange at first. On the other hand, if I was to go to the US, there are certain cultural identities I could never have. For instance, as a white guy, I could never be treated as an African American, no matter how much I wanted to be or tried.