Tomioka Yuuka didn't show her emotions that often and got used to isolating herself. Consequently, this caused people to turn away from her for her quiet attitude. She didn't mind being alone too much for... personal reasons, as long as Seiji and his daughter, Yui Komori, were by her side. One day, Seiji decided to send them to live with acquaintances in Japan while he moved abroad for work. The girls found it odd, but they didn't question their father figure's actions and complied. They realized too late that they made the biggest mistake of their lives. The mansion where they were sent belongs to a family of vampires, composed of six sadistic brothers and thirsty for human blood. Torn between saving herself and Yui from being completely drained of their blood while being held in false imprisonment, Yuuka seeks to understand the secrets hidden among the shadows while the youngest of the family slowly develops feelings for her.