After Shizuka Hio's death, peace is restored at the academy. As usual, Yuki is busy with her duties as Guardian when Zero, who has been gone for quite some time, comes back.

Yuuki and her friend Yori walk through the nearby town, and encounter a lost boy. Yuuki offers to take him back to his parents, and the child takes her to an abandoned building. He kisses her in gratitude, which knocks Yuuki unconscious. She awakens to find Kaname watching her. Kaname reveals that there is a party for vampires in the building, and asks Yuuki not to leave the room. Meanwhile, Zero has been assigned to oversee the party by the Hunter's Association. The child goes to Yuuki's room to apologize, and Yuuki follows him. She views the party as Kaname enters, and Hanabusa's father offers his daughter in marriage to Kaname. Yuuki returns to her room, and Kaname returns. He lies down beside her, and asks if she wants to be a vampire and live forever with him. She agrees, and Kaname leans down to bite her neck. But before he can, he pulls away and apologize and says that he will not hurt her.

The students of the Cross Academy leave for the holiday, and Rima, Ruka, Kaname, Akatsuki, and Takuma go to the Aido family residence; however, Hanabusa stays on campus. Shiki goes to his home rather than the Aido residence, as he was summoned by his uncle. In the Night Class dorm, Hanabusa recalls asking Akatsuki to investigate Kaname's family while at the Aido residence. Hanabusa goes to the Day Class dorm, and meets Yuuki and Zero, who makes dinner for him. Afterwards, Hanabusa takes a bath and recalls meeting Kaname when he was younger, noting the change in his personality before and after Kaname's parents died. While making dinner, Yuuki cuts herself and tells Zero to drink the blood, a scene witnessed by Hanabusa. He returns to the Night Class dorm and enters Kaname's study, where he realizes Kaname is planning something.

While the Night Class is at the Aido family's vacation home, Yuki, driven by her desire to stop hurting Zero, tries to regain her memory of the past and becomes haunted by even more powerful visions.

Kaname asks Yuki to be his lover. The Night Class guards begin accompanying her everywhere, and Yuki cannot hide her embarrassment. Why does Kaname go to such great lengths to protect Yuki?

Senri returns to the Academy, but upon having a confidential talk with Ichiru, he becomes noticeably different from before. The insolent Senri goes to see Ruka who has been locked up in her room since she got word of Kaname's new girlfriend.

Yuki wakes up a vampire, and her memory of her childhood returns. She now remembers her father, her mother, and her brother. Despite her mixed emotions, Yuki cannot suppress her vampire instincts.

Yuki now understands who she really is. Worried about Zero, she sneaks out of her room to find him. Zero cannot accept Yuki's new self, and he points the Bloody Rose gun at her.

Absorbing Kaname's blood finally revives Rido. The vampires all suspect this, and an unsettled mood enshrouds the Academy. The Headmaster calls for an emergency evacuation of the Day Class students, as Rido's servant vampires begin attacking the students.

In order to protect the academy, the Headmaster confronts the head of the Hunter Society while Rido is still on the rampage. In the meantime, Ichiru pays a visit to Zero and shoots him with the Bloody Rose gun.

Yuki understands the position she has been put in, and remembering Kaname's words, "Do what you have to do," Yuki decides that as Guardian, she must protect all the students at the academy and fight Rido.