|Dr. Ciel and Passy|
|First Appearance||Megaman Zero|
During the first game, she is a scientist working on the creation of a substitute energy source because she believes that it will stop the war between Neo Arcadia and the Resistance. She convinces Zero, who suffers from memory loss, to fight together with them to defeat Neo Arcadia and their leader, Copy X, who is a copy of the legendary X from the Megaman X series. It is revealed later on in the game that Ciel herself was the one who created Neo Arcadia as a utopia where humans and reploids could live in harmony, and Copy X himself to lead it, as the original X's body was lost.
During the second game, Ciel is still working on the substitute energy. After Elpizo's betrayal, she acts as the commander of the resistance.
At the beginning of the third game, Ciel has succeeded in creating the substitute energy source, the Ciel System.
Ciel now, leading Resistance Base in trailer. Which is near human city and campaign.