Cross Academy Night Class is the first chapter in the Vampire Knight manga. Yuki Cross is a young, 15 year-old girl who attends a prestigious school called Cross Academy, of which her adoptive father is the headmaster. In this school, there are two groups of students: the Day Class and the Night Class. The students part of the Night Class are all in possession of a dark secret, one that almost no one in the school is aware of: they are Vampires. It's the job of Yuki Cross' and Zero Kiryu's job as the School Guardians, or prefects, to maintain balance and order in Cross Academy.
A little girl lost in the snow is attacked by a vampire. Another vampire comes and kills the first by piercing his head with his arm. He licks the blood and asks the little girl if she is okay. This is Yuki's first memory from ten years ago. Today Yuki stands outside the Moon Dormitory at twilight trying to keep a herd of girls back from the building. The gates open and a number of beautiful and attractive individuals exit, the Night Class. The school girls overwhelm and crush Yuki. She is helped up by Kaname Kuran. Yuki jolts to attention, confronted by her crush, also the boy who saved her ten years ago. She thanks him and smiles at her and says that her formal manner towards him makes him feel lonely. Yuki protests its because he saved her life. Kaname tells her not to worry about it and he jostles her hair, but his arm is torn away by an angry Zero Kiryu. He coldly tells Kaname that class has started and Kaname tells him he is scary. A Day Class girl comes up with Kaname and asks him to accept her rose. He accepts the rose and thanks her for it. Zero looks at Yuki sideways and tells her its not his business if she likes Kaname, but she has to understand. Yuki pouts and says she knows that they are different from them, because they are vampires. Yuki and Zero continue their job and Yuki beats up Zero when they are finished, telling him off for being late.
Zero protests with the Headmaster about their job, complaining that Yuki is not very good and wants someone else to help. Yuki fights back complaining that he is always late or leaving early. The Headmaster says he cannot allow anyone else to do this thankless job which is necessary, but he doesn't have to worry if his children do the job. Zero angrily smashes the desk in half, saying he is not the Headmaster's son as he wasn't adopted like Yuki. He asks Yuki to plead with the Headmaster, Yuki objects saying its not going too badly and she's happy to help. The headmaster is delighted that Yuki understands his pacifism of wanting humans and vampires in harmony. Zero leaves amidst the Headmaster's flamboyant rant. Yuki left behind says to the Headmaster that she understands where Zero is coming from. The Headmaster comments on how vampires attack humans and if people found out the truth it would cause an uproar. Yuki protests that Kaname is different and therefore with vampires like him, pacifism is possible. She tells him that things will be okay and happily jumps out the window to return to her patrol. Yuki reflects on how she has no memories before she was saved by Kaname, that night he took her to the Headmaster who looked after her ever since, that incident she suspect is why she wants humans and vampires to be friends.
The following day, Yuki sleeps in class, as does Zero. The teacher assigns them a detention, Yuki awakens with a yawn and complains. Sayori sits beside her commenting on Yuki's unusual life, that Yuki is like a vampire, Yuki shocked asks Sayori if she believes in vampires. Sayori denies it. Yuki asks Sayori to join her in detention, complaining that Zero is no fun, Sayori refuses saying Yuki and Zero get along okay. Yuki protests, complaining about Zero's personality within his earshot, Sayori adds to the comments and Yuki makes a face at Zero. Sayori leaves to Yuki's protests, commenting that Yuki is the only one that can handle Zero. The Night Class attends a class discussing the blood tablets. They discuss how the Night Class is the first of its kind. Yuki stands watching Kaname from afar. Zero standing watching in another direction, asks Yuki how Kaname is. Yuki protests, saying she was only checking that everything was ok. Zero tells her how he doesn't trust the Night Class and is looking to find the best way to kill them. Yuki reflects on how Zero hasn't changed in the four years he lived with them. From the building above, Yuki sees two Day Class girls on the ground. She jumps, grabbing onto a tree to break her fall, she orders the girls to return to the dorm, when she sees one of the girls bleeding she tries to hurry them back. Yuki pulls out her weapon demanding to know who is there. Two vampires, Hanabusa Aido and Akatsuki Kain stand there to the delight of the two other girls. Kain brushes away Yuki's weapon. Hanabusa comments on the sweet smell of blood that drew them there. Yuki warns him not to touch the girls. Hanabusa touches her hand and says it is her blood he smells. He grabs her hand and draws her closer. Yuki struggles realizing she cut her hand on the tree. He licks her blood and asks if he can drink from her neck. Zero suddenly appears holding the bloody rose to Hanabusa's temple reminding Hanabusa that blood drinking is strictly forbidden, asking him if he's lost his mind.
Yuki yells at Zero to stop, but as Aido says he's already tasted Yuki, Zero shoots. Yuki pushed Zero's gun out of the way in time, shocking Aido and Kain. Kaname appears and asks Zero to put away the bloody rose. Kaname takes Aido away, asking Zero if it is okay and telling Kain off for not stopping Aido. Kaname asks Yuki to take the girls to the headmaster to get their memories wiped. He apologizes to Yuki for scaring her. She protests that she is fine, reaffirming in her mind that Kaname is different from the rest of the vampires. Zero grabs Yuki's hand and uses his tie as a bandage on her hand. He tells her they are leaving, Yuki reflects that for the last four years Zero hides something. Zero tells Yuki that the proof that they are beasts is in the fact they are attracted to the smell of blood. Yuki dries her hair, still thinking about Zero and his secrets. Zero comes barging into the bathroom. Yuki protests his entry, he complains that the dorm bathroom is closed and takes off his shirt. Yuki throws something at his head telling him not to tell undress in front of a girl. Zero is silent, making Yuki angrier when she realizes he probably doesn't think of her as a girl. Zero leans over and smells Yuki to her surprise. He tells her the smell is gone and Yuki tells him to shut-up as her hand has already stopped bleeding. She comments how this is her second time almost being bitten and wonders if her blood is particularly tasty to vampires. Zero asks her how he would know and she agrees, continuing to dry her hair, exposing her neck, where Zero's gaze lingers upon it. Yuki promises to be careful as it would be disgraceful to have her blood drunk as a guardian. Aido wonders if the blood tablets aren't working for him anymore as he couldn't resist Yuki's blood. Kaname slaps Aido, leaving a mark on his face. Aido apologizes and Kaname licks his fingers.