The story tells the story of the only two pure-blooded families left in the vampire world - the Matsuyama and Miyazawa families. The three elders in the vampire world were dissatisfied with the Matsuyama family's marriage to human women, and began to pay attention to the Miyazawa family, which they had never paid attention to. The story takes Yu, the only daughter of the Matsuyama family who has not yet awakened, as the protagonist. You didn't know that his family was a vampire family. He had lived with his mother since he was a child, and his father came back once a week. It wasn't until You was fifteen that he moved to his father's house to live with three brothers he had never met before. While going to school, he learned about the family's work so that he could inherit the family's work when he grew up. Living with the three brothers, You will learn the truth of everything.