Half people can't be divestors. She just picked her other side.
I just wish she opened her mind bigger than the Nigeria vs Japan thing. There are other countries in the world that her Japanese passport can get her to, which the Nigerian passport can't. I was a little bit sad when I heard she went out of her way not to learn English, because the rest of the English speaking world will be far kinder to her as a half black person, than the Japanese one. The adult ostracization and child bullying of half black people out there is horrible.
Non-coincidentally, half white Japanese are like demigods out there. Yes Japan is a homogenous nation, but they have a clear preference for a specific kind of outsider
I wish her luck.