Sierra appears to the Magic Knights when they first return to Cephiro. She is here pretending to be Presea, telling the Knights that Princess Emeraude had wished for all those who had died to be brought back to life. However, this was untrue, for it was impossible for anyone, even the Pillar to bring back a life. She does this to keep the Knights from feeling guilty over her sister's death.
Clef later reveals that he asked her to pose as Presea, for the sake of the Magic Knights and Ascot. When he asked her her what her real name was she simply said that she was Presea. She also silently admitted to herself that it was out of her love for Clef. She also opted to admit her's and her sister's feelings for Clef, but decided against it.
Though she cannot create weapons out of the legendary ore Escudo like her sister, Sierra does have the ability to retrieve any lost weapon. With this ability, she assists Hikaru after Nova breaks her sword. When in the process of retrieving weapons, Sierra wears the exact same gown Presea wore when creating weapons.
Sierra looks exactly like Presea, save for a birthmark on her chest, first pointed out by Cardina once when the girls were bathing. Her identity is found out by Alcyone, to whom she confides that as long as she can help Clef, she doesn't care about losing her identity as Sierra.
- Sierra does not appear in the manga. Presea had died earlier on in the anime, however this did not occur in the manga. To cover up this plothole, Sierra was created to take Presea's place.
- She is named after the Ford Sierra.