Yuuri

A Puella Magi with a mysterious past, she repeatedly clashes with members of the Pleiades Saints for unknown reasons. (Source: Puella Magi Wiki) She is not the real Yuuri Asuka. Her real identity is Airi, a close friend of Yuuri. When Yuuri died, Airi made a wish to become Yuuri. She has a grudge against the Pleiades Saints and wants to take her revenge on them.