Yuki's earliest memory is of a stormy night in winter, when she was attacked by one vampire and was saved by another, Kaname Kuran. Ten years later, Yuki Cross, the adopted daughter of the headmaster of Cross Academy, has grown up and become a guardian for the school, with two purposes: To protect the Day class (humans) from the Night class (vampires)'s fang and protect the true identity of the Night class students from being discovered by the Day class students.

Kaname Kuran, Yuki's saviour, leads the group of night class, with the help of Takuma Ichijo. But also at her side is Zero Kiryu, a childhood friend who was born into a family of vampire hunters and whose hatred for the vampires that destroyed everything he held dear, is now determined to kill them all and never trust them. And also Zero is a vampire himself. This coexisting arrangement seems all well and good, but the question remains: Have the vampires truly renounced their murderous ways, or is there a darker truth behind their actions? Is Kaname's infatuation with Yuki the beginning of a forbidden romance, or is it something in her forgotten past that draws him to her?

In this world of secrets, nothing is as it seems. And the price of misplaced trust may even be worse than death.