Dark skin and the amount of melanin does not equate to somebody being African, look at Kat's face she looks Asian (Which isn't a surprise considering that she comes from a game made in Japan.) in her own world she isn't from any country we know, but it's obvious she is supposed to look Asian, and would probably be from a country in Asia where people have a darker skin tone.
Emmett however looks as though he is obviously African it isn't just the skin color it's the entire facial structure.
She has darker skin, but she is definitely not African and she doesn't have the facial structure either. It always pains me to see Americans proclaim how "open minded" they are and how they aren't "racist" and yet say anybody with a darker skin color is "black" when each ethnic group have varying skull structures, and facial features to help them adapt to living in their part of the world. And of course there isn't really anybody who is "black" or "white" it's just different shades of brown depending on the amount of melanin in the skin. --- "Greater love hath no man than this, that a man lay down his life for his friends. John 15:13"
Kat is from the Cloud Village. She accidentally sent herself to space using some gravity jutsu. Was lost for some period of time. Got amnesia, gained new memories, and went to the world in which Gravity Rush takes place.
IT WAS SO OBVIOUS ALL ALONG /s --- 3DS Friend Code: 4081 - 5968 - 9750 XBL and PSN: Nekaito