citizen-means that you are loyal to your country and that you were probably born in that country citizen is when you are from another country If you are born in America, you are a citizen of America. If you're born in Japan, you're a citizen of Japan. Get it?
I'm not sure if this is true, but you have to live there for a number of years and you also have to be Japanese. I, myself, am not Japanese, but my friend is. And she says you have to be Japanese or at least half to be considered a citizen of Japan, but there may be other ways to be a citizen.