I saw this wallpaper of Yuna and another person, and I don't know who person on the left is.
I assume that it's Koda Kumi, because this art is used on her Real Emotion/1000 No Kotoba single and it was used in the video of Real Emotion.
But I haven't played FF X-2 yet and I don't know if she's a character in the game or not. Anyone know who she is?