Ritsuka Tachibana lives a calm and unchanging life. Her life begins changing bit by bit when Shikou Academy student council president, Rem Kaginuki, calls on the girl, and she begins having mysterious encounters with the student council members. One day, she comes home to find her mother collapsed with suspicious hooded men nearby. They were not humans but devils, vampires, and exorcists seeking the Forbidden Grimoire. Ritsuka's former daily life crumbles around her, and she finds herself slowly becoming attracted to Rem, who helps her in her predicament. On the other hand, confusion deepens with regard to her brother who carries a secret. Ritsuka is unsure what path to choose as she finds herself at the center of a love story.

(Source: Anime News Network)