Trigger of Conviction (断罪の銃爪 Danzai no Juu Tsume) is the fourth episode of Vampire Knight Series.
The episode begins with Yuki shocked at just discovering that Zero is a vampire. Kaname can smell Yuki's blood, so he rushes out of Headmaster Cross's office.Zero tries to approach Yuki, but Kaname appears and steps between Yuki and Zero. Yuki believes that Kaname will hurt Zero, so she tries to stop him and then faints. Kaname carries Yuki away to the infirmary and puts a bandage over the spot where Zero bit her. The Headmaster sends Kaname away to calm down the Night students who are able to smell blood while he talks to Yuki about Zero. Headmaster Cross explains to Yuki that Zero, his parents, and twin brother were attacked by a vampire, and Zero only barely managed to escape alive. This vampire was a Pureblood, so this caused Zero to eventually turn into a vampire himself.
Over at the Moon Dormitory, Aido can tell that it was Yuki's blood he was able to smell even though no one told him anything. Meanwhile, Zero reflects on what has just happened. Yuki walks by the Headmaster's office while Headmaster Cross is discussing Zero's fate with Kaname. Yuki overhears them considering sending Zero in with the Night students causing Yuki to run off disappointed. Yuki does not feel comfortable knowing that Zero may be put with the Night Class students because Zero hates vampires more than anything.
The next day in school, Sayori mentions something about Zero not showing up for class. Sayori also notices that something is bothering Yuki, and saw that she has an injury on her neck. Yuki lies, stating that she got scratched by a tree branch while out on patrol last night. Then, in the middle of her lessons, Yuki runs off worried about Zero. She heads to the Moon Dormitory while passing the gate keeper. During this time at the Moon Dormitory, two men are trying to recruit Aido for doing some research, but Aido makes them leave as Yuki approaches. Aido makes the two men leave, then asks Yuki what does she want. Yuki says that she's hear to talk to Kaname. Aido tells her to follow him. When Aido is on the staircase, he inquires as to who made the fang marks in Yuki's neck. It was revealed that Aido took off the bandage off of Yuki without her realizing it. Yuki refuses to admit that it was Zero.Aidou becomes irritated because he does not know why Kaname thinks Yuki is special. Aido attacks Yuki with ice, causing her to be frozen enough where she cannot move as he continues to figure out why she is so special. At this time, Kaname appears, cancelling out Aido's ice powers, and slaps Aido causing him to stop and apologize. Kaname tells Aido to go to his room and Aido does so.
Kaname apologizes to Yuki and tells her that he likes her just the way she is. Kaname does not want her to come to the Moon Dormitory alone anymore, so he tells her to bring Zero next time. As Kaname directs Yuki to the door, she asks why he doesn't treat Zero very well. He replies that he is upset that his "precious girl" has been bitten by another vampire. Yuki begs Kaname not to put Zero in with the Night students, but Kaname cannot follow her wishes. Before Yuki runs off, Kaname tells her the sad truth that Zero will eventually turn into a Level E vampire. Akastuki confronts Kaname about his obsession with Yuki, but does not get a very good answer.
Yuki walks slowly reflecting on the recent events. Meanwhile, Zero takes his Bloody Rose out. He holds it against the side of his head just when Yuki walks into his dorm room. Yuki tries to stop him, but Zero puts her in a position where Yuki is holding the gun to Zero's neck. He tries to get Yuki to shoot him, but Yuki cannot make herself do such a thing. Zero leaves the gun with Yuki as he leaves the room, but Yuki puts it down and chases after him. She catches up with him, and says that she will never be afraid of him and will always be his ally.
The Head of the Vampire Hunter's Association summons Headmaster Cross to tell him that someone will be coming to Cross Academy to see if Zero is a threat. If Zero is in fact dangerous, he will be shot without hesitation.
Fang of Repentance
Feast in the Moonlight