Pretty Pretty Please I Don't Want to Be a Magical Girl

The pilot follows Aika, a self-proclaimed "normal girl of average talent", as she begins her first day of high school. While talking with her new friend Zira in the cafeteria, Aika's ordinary day is interrupted by the entrance of magical villain Eclipse. Zira's attempt to stand up to him forces Aika to reveal herself as magical girl Star Guardian: Guardian of the Stars. Though Zira is delighted by Aika's magical girl identity, Aika herself is unenthusiastic, quickly dispatching Eclipse using a magically-summoned lead pipe. Eclipse teleports away after his defeat and speaks with the woman who empowered him, Lady DeVoid, who is pleased to hear that he was able to find Aika.

(Source: Wikipedia)