Secret is the second chapter in the Vampire Knight manga.
Girls from the Day Class enthusiastically prepare chocolates for their crushes. Hanabusa was sleeping when he is then bothered by the noise of the Day Class girls. His roommate and cousin Akatsuki looks out the window to see all the Day Class girls and realizes that is it St. Xocolatl's Day. The girls are crowded all around the Moon Dormitory trying to catch a glimpse of their idols.
Yuki stands atop the walls of the Moon Dormitory, blowing her whistle trying to regain control of the girls and send them back to class. Nadashiko Shindo, a Day Class girl tries to climb the walls, causing Yuki yells her to stop, but not before the girl falls and is caught by Zero. Zero coldly tells her and the other girls to come back at twilight because the Night Class will not leave their building during the day and warns them that the event may be canceled. The girls leave, but not before telling Zero he is too mean. Yuki tells Zero to be careful or he will become their enemy and won't get any chocolate at all. Zero points out that is the only option to keep the secret of the Night Class. Akatsuki yawns and states he is looking forward to sunset and the festival, while Hanabusa snuggles up in bed looking forward to the chocolate.
Headmaster Cross lectures Zero and Yuki in his office, asking them to be extra vigilant. Zero wants to cancel the event, but Kaien declines saying there will be a riot because it helps the kids let off steam. He dreamily discusses how beautiful the vampires are and what good allies they would make while Zero goes thundery and Yuki makes a joke about not flattering the vampires in front of Zero. Kaien talks about how the vampires have been enemies of humans since ancient times, but there are vampires who want to make peace and he wants Zero to understand his desire for co-existence eventually. Zero declares that impossible unless his past disappears. To relieve the tension, Yuki gives out her Xocolatl's gifts, Kaien is jubilant, but Zero notes that it is the same gift she gives them every year. Yuki tells him to shut up and grabs him by the arm and drags him to class.
As Yuki pulls Zero to class, Yuki recalls how Zero's family was killed by vampires years ago and wonders why Kaien wants to provoke Zero's pain. Zero's expression goes hard and he rips his arm from Yuki's grasp and she apologizes for dragging him along.
Toward the end of the school day, the girls are beginning to get excited again. Yuki asks Sayori Wakaba if she is giving chocolates to anyone. Sayori confesses that she doesn't fancy anyone in the Night Class and would prefer the Day Class. She asks the same of Yuki after noticing Yuki's ribbon. Yuki confesses her homemade chocolate didn't turn out and she had to resort buying chocolate. Sayori asks who Yuki is giving it to and noticing Zero's angry aura. Zero bursts out in anger from behind knowing Yuki is going to give chocolate to Kaname.
The Day Class have been organized behind gates with each of the Night Class' names and the Night Class disperse and go to accept their chocolates with Yuki directing everyone to behave. Hanabusa goes running off enthusiastically but is warned by Kaname to behave. Kaname accepts chocolates until his hands are full and begins to leave. As Yuki realizes she hasn't given her chocolate to Kaname, she gets shoved over by the crowd and drops her chocolate. Zero picks up her chocolate and throws it to Kaname telling him he dropped it. Kaname thanks Yuki for the chocolate. Yuki punches Zero for giving it to Kaname without her permission and he tells her he was getting irritated for delaying. Yuki thought she would be inconveniencing him and admits that his world is so different from hers. Seiren offers to carry Kaname's chocolates, he gives her all of them except Yuki's and tells her she can have them as the only one he wants is Yuki's. Yuki pulls up a red card on Hanabusa who is asking girls for their blood type, she pushes them apart and suddenly notices Zero has disappeared.
Zero struggled, sweating and having trouble walking back to his room, he senses someone's presence hiding around the corner. Nadashiko is trembling clutching chocolate, she thanks him for saving her earlier that day and offers her handmade chocolate to him. He yells at her to leave and punches the wall, she runs off apologizing. Night falls and Kaien, wrapped in a blanket, stares out a window. He talks to himself about the vampires before he notices Zero slumped in a corner. Kaien looking sad, tells Zero he cannot run away from his problem, but he is always pushing himself. Zero tells him to shut up, but has another attack. Kaien gives him a pill and some water, but Zero shoves it away. Kaien warns him that things will start changing from now on.
Yuki exhausted, makes her way back to the bathroom at the headmaster's house. she finds Zero slumped on the floor, his hair all wet. Concerned, she asks him whats wrong and dries his hair, she tries to put his shirt on him, all the while Zero is despondent. She pauses, then pulls from her pocket a chocolate and unwraps it, she places it in Zero's mouth telling him he was no longer able to say she gave him the same thing every year. She smiles proudly telling him it was her only successful homemade chocolate and that it was the only one of its kind. Zero has a sour look on his face and she jumps up and turns away. Zero blushes slightly after she has turned away. Yuki leans down and picks up the blood tablet and wonders why it is there.
Takuma Ichijo voices his concern that Zero doesn't look so well as Kaname stares at his chocolate. Kaname tells Takuma that Zero can't help it because of the incident four years ago.