God-given ability... pure and simple. I can never praise Mattari's work enough. He's draws the best, if not, one of the best, Yuuka I have ever seen. Without question.
BluRay said: It's more because of the expressions he gives the characters rather than the technical skill involved. That said, he still has the best Yuuka ever.
He also makes a good Komachi, still love that drawing about her holding bread in her mouth while wearing pink jumper suit (ala Mario)