Yui Komori's ordinary highschool girl life takes a new turn when she has to move to a new town for her new highschool,and on top of that she has to live in a place called haunted house with six vampire brothers.

It is the first day of new high school for Yui, with Ayato and Kanato in same class as her, she will be having a really hard time as Ayato will force her to do everything he want and even drink her blood. But how will Yui respond?

Yui finally finds out that why all the brothers don't get along with each other. Ayato challenges Shu a dart match, and the winner's prize will be Yui

At school, Yui makes a vain attempt to contact her father, and even her attempts to be friendly with Kanato go wrong. Later, she is caught by Laito, which leads her to a disastrous result.

Yui is still picturing the event when Laito was sucking her blood and told her why she was brought here, but she is later confronted by Kanato who sucks her blood in the graveyard. Later she confronts Reiji who also feeds on her.

Kanato takes Yui to the sacrificial bridal room where he almost kills her, but stops when Ayato tells him that Reiji wants to see him. Later, Subaru tells her to escape, but she decides not to, so Subaru gives her a silver knife which can kill vampires.

Yui is awakened by the sound of rain and looking down from her window, she sees a mysterious woman in a purple dress. She becomes controlled by an unknown force, and walks all the way down to a secret tunnel and enters through a door that takes her to the past. There she sees Ayato, Kanato, Laito, Shuu, Reiji, and Subaru as children. But after she discovers the truth of their twisted past, she reappears in the tunnel with a worried looking Ayato in front of her. And when being joined by Laito who was looking for some "fun" Ayato leaves shortly after saying he's had "Enough of this", and once again reappears looking down a balcony in deep thought.

Yui asks the triplets about the woman in the purple dress who she spotted in the garden, and learns the gruesome truth about what befell their mother. Yui runs out of the house in horror and collapses sobbing in the garden, only to be approached by Subaru, who demands she keep her distance from him, or else. Yui spends a sleepless night in her chamber, made less restful by the arrival of an unwanted guest.

Yui experiences more chest pains and leaves the mansion in the middle of the night to seek answers and finds Shu in an abandoned church. At first, he is unhelpful but quickly becomes interested in obliging her request for answers by forcibly tasting her blood to verify that is has indeed changed somehow. Richter then appears and takes Yui to the secret room where 'Cordelia' awakens and everyone feels it especially Ayato who finds Yui's rosary on her bed.

Cordelia and Richter savor one another's company for the first time in ages, until Ayato interrupts, demanding to know what they have done to Yui.

While Cordelia and Richter catch up, Reiji appears, and Cordelia begins to tease him in a seductive way. He then rejects her, and Laito, Kanato, Subaru, and Shu all appear due to the commotion. As they discuss the situation, she gives a knife to Ritcher so he can "dispose" of all the boys for her. Richter does not follow suit, as it is revealed that he must kill Cordelia, much to her chagrin. Going after her heart, Ayato appears and tells the two to end the bickering, and that Yui belongs to him. As he and Ritcher duel in attempt to win Yui, Ayato is stabbed. Just then, Yui regains control of her body, and calls for Ayato. She then stabs herself in the heart in order to save everyone. Richter attempts to take Yui's heart, but is stabbed by Ayato. At that moment, Cordelia takes over Yui's body once more.

eturning from when Yui stabbed herself, Subaru takes out the silver knife. Richter then struggles to the attic where he's hidden Cordelia's dress, however Laito finds him there and prevents him from using the dress to keep him alive. Meanwhile, Shuu, Subaru, Kanato and Ayato are watching over Yui and the awakening takes place. Reiji makes a potion to kill Cordelia while in Yui's body, but in order to make the potion complete, he must have a piece of Coredlia. Kanato pulls apart his Teddy to reveal a vile containing Cordelia's ashes. This makes the potion complete. Switching back to the attic, Laito sets fire to the dress and Ritcher, which then the fire kills Ritcher. Ayato then drinks the potion only to feed it to Yui through a kiss. Yui then awakens, and notices all the brothers are with her. After the credits end, we see all the brothers talking to Yui, one-by-one. Resuming the episode, we see Yui on the balcony holding a rose, Ayato then walks up to her a returns her cross necklace. We then see the rose falling and the petals falling off, and chains locking Cordelia in the attic.