According to an artist comment in the Kingdom Hearts Ultimania guidebook, the Final Fantasy characters seen throughout the series are considered parallel universe versions rather than directly originating from their home series. However, as revealed by series creator Tetsuya Nomura in the Kingdom Hearts Series Ultimania Alpha guidebook, there is one exception to this: Auron from Final Fantasy X, who appears in Kingdom Hearts II in the Underworld area of the Olympus Coliseum world. Nomura's explanation for this is that the Underworld is linked to the Farplane from Final Fantasy X, both being gathering places for the dead. He also admitted that while he was initially concerned that Auron's Japanese-style clothes wouldn't fit in the world, he ultimately didn't change much of his design aside from removing his sunglasses and making him younger.