Mirage Koas

Quiet and mild-mannered, Mirage is an excellent fighter, as befits the daughter of a dojo-owner. Cliff learned to fight at the same dojo club and throughout their youth had many matches.

On Elicoor II, Mirage splits up from Cliff and Fayt, going about helping behind the scenes. She joins the combat party formally upon the return to Elicoor II, after Styx, on the second disc. Mirage can be recruited on the Diplo.

Mirage, like Adray Lasbard, is a character that was made playable in combat only with the release of the Director's Cut version of the game. Unlike Adray, who didn't exist at all in the original Japanese version, Mirage was simply a non-playable character from beginning to end.

(Source: Star Ocean Wiki)