Those two are the same, if you are born and brought up in Japan then you are Japanese. Similarly if you are born and brought up in America then you are an American even if you happen to look like most people do in Japan. Do you disagree with this? Can immigrants from Japan never become true Americans? Or have you accepted Japanese racism to such a degree that you think it is impossible for a white person to become Japanese?
Also, the fact that you see someone who lived in Japan for 10 years as anything other than Japanese is a sign that this is a larger problem and not just something in his mind. Would you call someone who have been integrated in American culture for 10 years anything other than American?