Her sister, Lightning.

As noted by her fiancé, Snow, several times in the Episode Zero: Promise, Serah and her sister share a number of physical attributes.

In particular are their strawberry-blond hair, heart-shaped faces and blue eyes. They are notably the only characters in the game with that hair color.

Her hair is a ponytail drawn to the left side and she wears a number of accessories: silver cat earrings, a necklace in the shape of Cocoon, a black band on her right bicep and a bracelet with red, yellow and blue jewels on her left wrist.

Her clothing consists of a red plaid pleated skirt with black lace on the bottom edge, a white sleeveless dress shirt with black buttons, a semi-transparent pink sweeper, black thigh-highs, and light brown ankle-high boots with white tips.

One thing to take note of is that Serah lacks the trademark zippers and belts that usually adorn most Final Fantasy characters designed by Tetsuya Nomura. That her clothes are considerably simple and less revealing that the usual female cast of Final Fantasy furthers her image as a sweet and innocent character.