Yui Komori, a normal 17-year-old high school student is forced to move to a new place due to her father's new job. The episode starts with Yui being dropped off at a mansion but then it starts raining. After she knocks on the door, it suddenly opens, which surprises her. As she enters the house, she doesn't see anyone there so she shouts out to see if anyone is at home. She turns to see a boy (Ayato) sleeping on the couch in the entry hall and tries to talk to him but he doesn't respond so she tries to wake him up but when she touches him, his body is very cold, so she tries to feel his pulse but she finds that he has no pulse. Scared that he might be dead, she tries to call ambulance but as soon as she takes out her cell phone, Ayato wakes up and snatches her cell phone from her and tells her that she is too noisy. Yui is shocked to see that he is alive even though he didn't have a pulse. Then suddenly Ayato pulls Yui and pushes her down onto the couch. He licks her neck before going in for a bite, but is stopped when Reiji appears, much to the Ayato's annoyance.

Ayato attacking Yui

Reiji tells Ayato that this room is for guests and tell him to take his private activities to his room. But Yui breaks free from Ayato and asks Reiji for help. He asks her who she is, and she replies that she is Yui Komori and her father told that she was supposed to live here. Reiji says that he wasn't informed about this so he asks Ayato if he knows anything about it but he doesn't know about it. Reiji tells them that this is not the place to talk and they should move it somewhere else.

Then she goes to the living hall with Reiji and Ayato. As Reiji asks her how she got here she is interrupted by Laito who seems happy to see a human girl in living hall so he licks her cheek and tells that she tastes sweet. Kanato suddenly appears and says he wants a taste too and licks her. Yui is irritated by this but is helpless. Reiji tells them to stop as their behaviour is impolite towards a girl they just met. Laito tells that everyone wants to taste something that is yummy, which Kanato agrees. Ayato, addressing himself as "Your's Truly", tells that them he saw her first so he will be her first everything. Out of nowhere, Subaru suddenly appears and tells that he is sick of Ayato calling himself "Your's Truly". Subaru tells that he smelled a human so his sleep was interrupted, and tells Yui how dare she interrupt his sleep. Surprised by his appearance, Yui asks him how did he entered the room, but Subaru gets angry and punches the wall telling her to answer his question first.

Subaru hitting the wall

Reiji then interrupts by asking everyone that if they knew about arrival of Yui. Yui tries to escape and tells them maybe there was some misunderstanding but Reiji tells her to wait for a moment because he wants to verify the truth. Shu, who is lying on the couch tells everyone that maybe he knew about her and tells everyone that the man told them to treat her with respect and not to kill her. At that moment they realized why Yui is there. She is the "Prospective Bride".

After which Reiji tells there is no misunderstanding and introduce every one to her and she finds them kind of weird as she wasn't told about being prospective bride. Yui doesn't believe this and replies by telling them that she needs to contact her father. However, Ayato still has her cell phone. When she tries to get it back, Ayato's teasing is interrupted when Subaru takes it from him and crushes it in his hand.

Subaru breaking Yui's cellphone

Then Laito, Kanato and Ayato start teasing her again so she tries to escape but she slips and injures her knee and blood comes out from her wound, causing everyone except Shu to rise. Yui figures out that all of them are vampires so she tries to stop them by rosary but they laugh and ask if she seriously believe a fairytale written by mortals. Yui then runs out of the room.

Yui getting injured by falling

As Yui runs through the mansion, she encounters the Sakamaki triplets. Kanato tells her that he will break her, Laito tells her she won't be needing a phone in this place when she tries to use a phone but its wire is cut. Ayato corners her at the front door and tells her she can't escape from him. With a taunting smirk on his face, Ayato tells her it is the much anticipated time to scream. But she manages to push Ayato away and runs up to stairs to a room where she sees a mysterious woman from the window but as the woman looks toward her, Yui feels a pain in her chest and when she looks again the woman is gone. Then Yui finds a diary and a picture of her with her father when she was a baby. As she starts reading an entry from the diary, she discovers that she was adopted. As she is still in shock, the Sakamaki brothers appear out of nowhere and asks her how she got into that room as it was completely sealed.

Yui with all six Sakamaki Brothers

Ayato, Laito and Kanato agains start licking Yui and Reiji tells that she must comprehend that she can't escape from them. To put in blunt terms, Subaru tells her that if she tries to escape, she is dead. Then Shu knocks over a picture to stop the triplets. The episode ends with Ayato about to bite Yui's neck.

Yui wakes up in her room and checks her neck for bite marks and is relieved to find out that she wasn't bitten. She doesn't remember changing her clothes and wonders what happened after she found out the truth about the six brothers. She wants to talk to her father and wish he comes soon. When she is about to cry, Laito, who is sitting next to her on the bed, tells her that crying won't help her and tells her that she looks pretty sexy in a sleeping suit. Laito tries to make a move on her as she smells so good but is pushed away by Ayato. Ayato tells him to not touch his things without his permission.

Laito answers, saying to not be so rough but Ayato tells him to shut up. He then says she is his - on which Yui pleads to stop. The conversation is interrupted when Reiji comes to tell everyone to get ready for school or they'll be late but Yui says that it is too late for school. Reiji tells her she is going to a night school as they can't let her be active during day time as she have common sense of mortal. After that he explain that as long as she is here, she must adjust herself and if she have any complaints she is welcome to leave any time. After everyone leaves her to change clothes, she thinks that it is a chance to go back to the abandoned room to check on her father's diary; however, as she opens the door she finds Ayato who tells her if she need help with changing. Yui slams the door and shouting: "No, thanks".

Yui watching the Sakamaki brothers while wondering why don't they get along with each other.

While on way to school Yui looks at all brothers and wonders that they are all siblings because they don't seems to get along well and they don't talk to each other much. Ayato asks what is on her mind while addressing as "Chichinashi" and Yui says to stop call her like that. Ayato tells that her opinion won't matter to him in his whole lifetime. After that, Reiji gives her cranberry juice and tells her to drink it daily as it is the best cure for anemia. Yui then thanks him but he says she hasn't to thank him as she is only a prey, leading to Yui being horrified and starts to tremble. After noticing it, Kanato tells his teddy that when human are scared their behaviour is funny in a sarcastic way.

Ayato sucking yui's blood

When they reach the school, Reiji tells her that she is in Ayato and Kanato's class and to go along with them. He tells her to don't do anything reckless unless she want a whipping. As Yui goes to her class, she sees its food prep time so Ayato orders her to make Takoyaki. Yui tries to refuse, but ends up making them. She says she is going to clean up and hurry back to class. Yui asks Ayato for help but when he appears behind her, she tries to run away. Ayato corners her and tells her that he has been holding his thirst since yesterday and he cannot hold back any longer. He starts sucking her blood finding it quite delicious and continues drinking. Just as she is about to faint, Reiji comes and tells him that he never imagined he would do this in school too. Before leaving, he tells him to be responsible and get her home safely.

Yui, waking up

After that, Yui wakes up in a swimming pool area in the house and Ayato is there with her. Ayato then takes Yui to the swimming pool and throws her in it, ordering her to tell him that he is the greatest and that she belongs to him. Yui struggles to get out and pleads Ayato for help as she can't swim. While seeing her begging for help, he has a flashback about his childhood where he too was almost drowning and asking his mother for help but, she just stood there and then left. After that,

Ayato kissing yui

Ayato finally decides to help Yui and jumps in the pool. Ayato grabs her hand and on seeing her faint, kisses her. When she wakes up, Ayato starts sucking her blood again in the water. He takes her out of the pool and says her blood is flowing in his body and it totally overwhelms him. Yui says "please make it stop", after which Ayato leaves saying that is enough for today and throws a towel at her.

After that an unknown man is seen standing in a forest near the house. At the end of episode Yui is seen going back to the abandoned room to find the diary. She is very happy to find it, however when she opens it she finds it completely blank. Yui is perplexed that everything that was written there just vanished as if no one had even written in it.