Yuki's earliest memory is of a snowy 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 "prefect" (also known as a guardian) for the school with two purposes: to protect the Day class students (humans) from the Night class students (vampires) and to protect the true identity of the Night class students from being discovered by the Day class students. Her fellow guardian, Zero Kiryu, a childhood companion whose parents were killed by a pureblood vampire, is now determined to kill them all and refuses to trust them. Through a cruel twist of fate, Zero becomes a vampire himself, having been bitten by a pureblood vampire four years before, Shizuka Hiou. Kaname, Yuki's savior, leads the group of Night class, with the help of Takuma Ichijo (the vice president).
The main differences between the anime and manga are the placing of the story and the finer details. Several events with the anime are rearranged (such as when Yuki is attacked, however she is attacked several times in anime). Also, minor details of how Yuki is attacked are also changed. Some scenes and details, like when Zero fires his gun, the Cross Academy symbol is shot out, or when Yuki follows a child with a red balloon or Aido's "Souveneir Collection", which appear in the anime but are not seen in the original manga. The scene where Kaname lets Zero drink his blood is also different in the manga.
Characters
Yuki Cross
The adoptive daughter of the headmaster of Cross Academy, Yuki is a member of the school's disciplinary committee, which is also known as Prefect (Guardian). Ten years prior to the events of "Vampire Knight," Yuki was attacked by a vampire, but was rescued by Kaname. She has lost all memory of her life before the attack because her mother, Juuri Kuran, used her pureblood powers to put her vampire side to sleep, and Headmaster Cross took her in as his own daughter. She, like Chairman Cross, believes that vampires and humans can live together peacefully. She has also been giving her childhood friend Zero her blood to save him from becoming a Level E vampire. She and Kaname were raised as siblings by Yuki's parents, Juri and Haruka Kuran, who were also siblings and heads of the Kuran line of pureblood vampires. She is also Kaname's fiance, whom she believes to be her brother, and Kaname has yet to tell her the truth about who he is. Yuki has feelings for Kaname who has always been protecting her and has been by her side during her childhood as a human and as a vampire, but also has a deep connection and strong feelings for Zero. When Rido Kuran, Yuki's uncle, resurfaces at Cross Academy, Kaname awakens her vampiric side and pureblood powers.
Zero's family was killed by the pureblood vampire Shizuka Hiou. Zero was taken in by the headmaster of Cross Academy, and became a Prefect, (Guardian) alongside Yuki Cross. He has a great hatred for vampires though he is revealed to be himself a Level D due to Shizuka's attack four years ago. He also has a younger twin brother named Ichiru who was living by Shizuka's side. Even though Kaname killed Shizuka, Ichiru thought it was Zero and blamed him. Zero assumed that Ichiru wanted revenge but instead he wanted death so he let Zero "eat him" making Zero complete putting him at a tier of power above vampires and hunters and possibly saving him from becoming a Level E indefinitely. Zero is in love with Yuki, always protecting her, and almost kissing her but restrains himself.
A pureblood vampire, Kaname saved Yuki from an attack by another vampire when she was little. He is the class president of the Night Class, much feared and respected by the other Night Class students. While he is cold and authoritative towards his fellows in the Night Class, he is always kind and sweet to Yuki. He has shown that he cares deeply for Yuki, and loves her in a romantic sense. (He allows Zero to live because he knows his death would sadden Yuki, and because Zero is useful).He is both jealous and angry of Zero for biting Yuki and endangering her life. He has a deep love for Yuki. They are also engaged, just like Haruka and Juuri, who were married to each other as it is common for pureblood siblings to marry. It is essential to keep the bloodline pure. Also, a fact yet to be revealed to Yuki is that Kaname is not her "true brother". He is actually the ancient ancestor of the Kurans, and Rido is his master who awakened him from his grave, making him unable to kill the man.