Yui Sasame, a descendant of vampires, struggles to fit in with her human classmates and often comes late to school. Her class representative, Sekiya, constantly criticizes her for her behavior. One day, after a heated confrontation, Yui feels an uncontrollable urge awaken deep within her — a reminder of the powerful instincts she inherited from her vampire bloodline. Torn between her human heart and vampiric nature, Yui must face the desires that could change her life forever.