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...

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...

Yuki learns that Maria's true identity is Shizuka, the pureblood vampire who bit Zero and turned him into a vampire. With this information, Yuki accepts a deal from Shizuka and offers her blood in order to save Zero...

Yuki and Zero are busy dealing with the Day Class students who are chasing after the Night Class students more fervently than ever due to the upcoming dance...

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...

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...

Maria's masked servant is none other than Zero's twin brother, Ichiru, whom Zero has not seen since their separation long ago...

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.

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.

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.