The episode opens with the students of Shikō Academy preparing for the Cultural Festival. Ritsuka is in the classroom sewing with Azuna as she reflects on what has happened so far. Although she still attends school regularly, she hasn't seen Rem since the incident from the previous episode. On the day of the Cultural Festival, Lindo uses his holy water and exorcist powers on Ritsuka to mask the scent of the grimoire. He also tells her to be careful since the festival is opened for the public because a devil or vampire could easily slip in unnoticed. Lindo suddenly touches Ritsuka's cheek and quietly says that he's glad the scratches he inflicted on her in the previous episode have fully recovered. Azuna later arrives and they head to school together. On the way, Lindo and Azuna firmly tell Ritsuka to not go off on her own and to have either of them accompany her wherever she goes. Ritsuka reluctantly complies and confidently declares that she won't let anyone find out that she is the grimoire, until after her seventeenth birthday is safely past. Lindo and Azuna agree with her and they assure her that they will make sure it happens.
They soon arrive at Shikō Academy and Ritsuka is amazed by the grandeur of their Cultural Festival. Since it is Ritsuka and Lindo's first time at Shikō Academy's Cultural Festival, Azuna also tells them to look forward to the evening party, claiming it is even grander. Meanwhile, in the 'Third Library', Shiki is looking for Roen until Rem appears and informs the student council that Roen won't be coming here anymore. He explains to them that Roen has betrayed them, because he was secretly still serving his previous master, the fallen king Lord Maksis, whom his father had sealed away. Shiki deduces that Roen was trying to get the grimoire in order to revive Maksis while Urie and Mage express their relief that Roen hasn't gotten it yet. Rem suddenly tells them that he's already found the grimoire. He lies to the Student Council that the grimoire was never in the Tachibana family because before his death, Professor Tachibana arranged for the grimoire to be hidden in a well behind a church in Vienna. He claims that he already sent his men to retrieve it before declaring checkmate on his shōgi board. After the student council leave, Rem places another shōgi piece on his board as he quietly tells himself that he never imagined the grimoire had been nurturing inside Ritsuka all this time. This clearly puts him in a dilemma because if he removes it from her, he would have obtained what his father wanted, but Ritsuka will die.
Meanwhile, Ritsuka and Azuna are working at their food wagon until Ritsuka notices her brother watching her intensely while squeezing himself between two wagons opposite her. Seeing this, Azuna agrees that Lindo has gone a bit too overboard and goes to stop him. After she is gone, Ritsuka is approached by a female student who informs her that she has a visitor. Ritsuka leaves the food wagon and is surprised to see Urie causing her to become cautious. He asks her to be his partner for the evening party, but she refuses. Urie asks her if she is still angry at them for persistently asking her about the grimoire until he is interrupted by Mage who pushes him aside. Mage apologizes to Ritsuka for snatching her away (see Episode 5) and he informs her that Rem found out that the grimoire was in Vienna all along. Hearing this, Ritsuka becomes confused and Mage asks her to be his partner for the evening party. He shyly admits that dancing isn't really his thing, but if she really wants to dance, he wouldn't mind dancing for her. Ritsuka refuses and while Urie and Mage bicker over her, Shiki surprises Ritsuka from behind and he asks her to be his partner for the evening party until he notices that she is not emitting her usual scent. Urie and Mage also notice this and the three begin sniffing her until Azuna appears and drives them away with her holy water.
Lindo shortly appears and is about to exorcise them, but he is interrupted when the fangirls suddenly appear to whisk the Student Council away. After they are gone, Ritsuka quietly asks Lindo and Azuna why Rem lied to the devils about the grimoire being in Vienna. Azuna tells her that Rem lied to prevent the devils from interfering with his search and that devils think of nothing but lies. The evening party soon approaches and Ritsuka attends it with Azuna. As they enter the ballroom, they are told by the hosts and hostesses to take a drink, orange for girls and grape for boys for the King and Queen game. Azuna explains to Ritsuka that in one of the drinks, a King crown, and a Queen crown is hidden in them. As part of the tradition, whoever gets the crowns will be crowned King and Queen of the evening party and will have to dance in front of everyone. Just as Azuna tells Ritsuka that the odds of winning the crown are against her, Ritsuka sips her drink and discovers the Queen crown in her glass, startling everyone. Seeing this, Urie, Mage, and Shiki hurriedly gulp down their drinks hoping to win the King crown, but neither of them wins much to Azuna's relief.
Ritsuka glances at the Queen crown wondering who the King will be until Rem enters the ballroom. The girls squeal with excitement at Rem's appearance as he is offered a drink. He sips his drink and discovers the King crown in his glass. Lindo shortly arrives and just as he and Azuna try to tell Ritsuka to get out of here, they are pushed away by the other students who crowd around Rem and Ritsuka. They are later seated on the thrones and Rem relieves Ritsuka from her nerves by telling her that it was just a coincident that their glasses contained the crowns. Urie, Mage, and Shiki display signs of jealousy while Lindo and Azuna worry over Ritsuka, but Azuna assures Lindo that the devils won't try anything in a crowded place. The music then begins and Rem offers his hand to Ritsuka. When she becomes hesitant, Rem impatiently grabs her hand and leads her onto the dance floor. Ritsuka protests that she cannot dance, but Rem just tells her to follow his lead. As they dance, Ritsuka awkwardly thanks Rem for helping her brother in the previous episode. Rem bluntly replies that he did nothing to earn her gratitude and he only did it to protect himself. Ritsuka retaliates by telling Rem that he is always like that. She continues saying that he always claims he does it for his own interests, and yet, he has saved her so many times which startles him.
As they continue dancing, Ritsuka finds herself feeling perturbed, leading into their song 'Someday Towards The Place We Saw In A Dream' ("Itsuka Yume de Mita Basho e" いつか夢で見た場所へ). It is then when Ritsuka and Rem realize that they are in love with each other. After the dance, there is a fireworks display and everyone rushes over to watch it, leaving Rem and Ritsuka with each other. There is an awkward tension between the two, but Rem cooly brushes it aside and leaves without saying anything to her. After the party, Ritsuka heads home with Lindo and Azuna. As they wait to cross the train tracks, Ritsuka glances at her Queen crown and quietly admits to herself that she really has fallen in love with Rem. They are later interrupted when they are suddenly surrounded by vampires who demand to know where the grimoire is. Lindo instructs Azuna to protect Ritsuka and they engage in a battle with the vampires. No matter how many vampires they annihilate, more keep appearing and Lindo is forced to transform. While this is happening, Jek suddenly appears behind Ritsuka and snatches her.
Azuna saves Ritsuka by lunging at Jek, slashing his cheek with her dagger, and in his rage, he impales her with his claws. Seeing this, Ritsuka screams in anguish causing her to unleash the grimoire which is emitted from her body in the form of a bright light. At Shikō Academy, the student council senses the presence of the grimoire. The grimoire's light destroys the surrounding vampires and Azuna dies in Ritsuka's arms. As the light begins to fade, Ritsuka breaks down into a hysterical grief and from afar, Jek laughs like a maniac. He triumphantly exclaims that he's finally found the grimoire for his master, Lord Nesta and vows to return and reclaim Ritsuka as soon as the light has completely faded. The episode ends here.