The Demon Girl Next Door

One day, Yuuko Yoshida awakens her dormant powers as a devil, also known as Shadow Mistress Yuuko, and her ancestor Lilith tasks her with defeating the Light clan's shrine maiden, a magical girl. Through her classmate Anri Sada, Yuuko meets the magical girl Momo Chiyoda and challenges her to a duel, but she loses quickly because she lacks strength. After that, Yuuko struggles with her role as a devil and her duels with Momo, often relying on her for help. By a strange coincidence, Yuuko also weakens Momo by taking away her power, and they end up working together to protect the peace of Tama city.