Cross Academy is attended by two groups of students: the Day Class and the Night Class. At twilight, when the students of the Day Class return to their dorm, they cross paths with the Night Class on their way to school. Yuki Cross and Zero Kiryu are the Guardians of the school, there to protect the Day Class from the Academy's dark secret: the Night Class is full of vampires. Zero warns Yuki to stay away from Maria Kurenai, the new Night Class transfer...

After suffering a mortal wound, Shizuka quietly dies in Ichiru's arms. Meanwhile, Yuki and Zero try to find where Shizuka may have gone, but Zero is constantly thwarted by his Level E seizures...

Tomorrow is the annual St. Xocolatl's Day, when it is customary for the girls at the academy to give chocolates to the boys. Although Yuki is busy patrolling the school grounds to catch the Day Class girls trying to sneak chocolates to the Night Class boys the day before the event, she finds time to make chocolates for Kaname as her token of appreciation...

As a duty of the Disciplinary Committee, Yuki and Zero must conduct a surprise inspection of the students' belongings at both the Sun and the Moon Dormitories. Just as they are about to enter the Moon Dormitory, Zero suddenly leaves the school grounds...

A new ethics teacher, Toga Yagari, arrives at Cross Academy. His looks, which are atypical for a teacher, are all the buzz among the Day Class students, and even Zero seems to have lost his usual composure.

Zero tried to sink his fangs into Yuki, but he was able to get hold of himself just before he succumbed to his urge. However, there is someone who is trying to kill him: the new teacher Yagari...

Yuki makes a secret decision regarding Zero, who is now determined to fight his affliction until the very end. Yuki feels guilty for betraying Kaname and keeping a secret from him...

Yuki has a lot on her mind after almost being kissed by Zero. She asserts that she will not speak to Kaname until he admits to Zero's innocence. While walking around town with Sayori, she comes across a lost little boy.

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 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.