Ritsuka Tachibana's tranquil existence takes a turn when Rem Kaginuki, the student council president of Shikou Academy, disrupts her routine. As she gets entangled with the enigmatic council members, her world spirals into chaos when she discovers her mother's collapse amidst unearthly beings like devils and vampires hunting the Forbidden Grimoire. Amidst this turmoil, she finds solace in Rem's assistance, even as her feelings for him grow. Simultaneously, the mystery surrounding her secretive brother adds to her dilemma, leaving her torn between conflicting emotions and unsure of her heart's desires.