Exceptionally ambitious high schooler Matthew has aspirations for a career in politics when he falls in love with his gorgeous 19-year-old neighbor, Danielle. But Matthew's bright future is jeopardized when he finds Danielle was once a porn star. As Danielle's past catches up with her, Matthew's love for her forces him to re-evaluate his goals.

Awakening her dormant abilities as a devil one day, Yuuko Yoshida aka Shadow Mistress Yuuko, is entrusted with the mission to defeat the Light clan's shrine maiden, a magical girl, by her ancestor Lilith. Yuuko meets magical girl Momo Chiyoda through her classmate Anri Sada, and challenges her to a duel, but loses quickly due to her lack of strength. Since then, Yuuko has struggled with her role as a devil and her duel with Momo, and borrowed help from her regularly. However, by a strange coincidence, Yuuko also weakens Momo by taking away her power to cooperate in protecting the peace of Tama city.