Emma has short blond hair and green eyes. She always wears a green cap turned around backwards with goggles around it, along with a white shirt over a black top. Her two-player version has reddish brown hair, blue eyes, and a blue cap.
Emma is a メカフェチ少女, a girl with a passion for mechanics. She loves cars and remodeling them herself, but she has a poor sense of direction. Therefore, she does not appear as a pilot in the Sonic Wings series.
Emma represents Spain in Lethal Crash Race, where she claims to be the "world's greatest mechanic." If the player wins the game using Emma, she shows off a new pink and white race car she created. She also appears in the endings for Takashi Uesugi, Juan Luigi Conte, and Carlos. In the US version of Carlos's ending, he calls her "Masako," but Japanese documentation for the game refers to her as Emma.