Yui Komori moves to a remote estate at the request of her father, where she meets the six Sakamaki brothers—Shuu, Reiji, Ayato, Kanato, Laito, and Subaru—a vampire family. Though the siblings are initially perplexed as to why the girl has arrived, they quickly learn that she is to be their new "sacrificial wife," in addition to their other, more carnal purposes for her. Yui instantly begins to wonder why her father would have brought her here and why she feels a weird, new aching in her chest after seeing the brothers. Yui's life as a slave takes a terrifying turn in her new home, with each brother more vicious than the previous. As her days morph into never-ending nights, and each of her brothers vows to make her his own, Yui falls deeper and deeper into madness and ecstasy.