Kaien Cross

Headmaster Kaien Cross (黒主理事長, Kurosu Kaien Rijich) is a character in the manga series Vampire Knight by Matsuri Hino. In the story, he is the current Headmaster of the Cross Academy. He is also the strongest legendary vampire hunter in history. He is the adopted father of Yuki Cross, the heroine of the story. Kaien's role in the story is largely observant and he takes little action until the hunter's association attacks the night class.

Background
Kaien was once friends with Juri Kuran in his youth, but following an unknown incident they lost contact and Kaien turned into a cold blooded vampire hunter, Kaien was known as the fangless vampire due to his notoriety. He was strong enough to have been considered to lead the Vampire Hunters Association. At some point he came to the conclusion he needed to kill all the Kurans as the strongest of the vampire clans, during this time he stalked Juri Kuran having not seen her for a longtime, but was defeated soundly by her. She bargained with Kaien to start a school where vampires and human could both attend.

With Juri's influence, Kaien took on Juri's dream and retired as a vampire hunter rejoining the family business of running Cross Academy 16 years prior to the story's beginning. Following the death of Juri and Haruka Kuran, Kaien took in their hidden daughter, Yuki after Kaname Kuran brought her to Cross for safekeeping. Cross kindly took Yuki in and adopted her within the week, becaming her very doting and slightly odd father, much to Yuki's annoyance. Kaien also took Zero Kiryu into his home several years later, he also wished to adopt Zero, but Zero refused.

Shortly after Zero's arrival, with Kaname's assistance, Kaien was finally able to establish the Night Class to promote understanding between humans and vampires. Zero refuses to attend high school and skips a year, but Kaien is able to convince him to attend the following year in order to prevent Yuki from being alone in the duties of being a guardian.

Personality
Kaien sports a happy go lucky personality yet can be serious at the same times, it can be said he is a little strange. He enjoys ribbing his 'children', particular Zero, who refuses to consider Kaien and Yuki family, which jokingly breaks Kaien's heart. He can appear very thoughtless, often overriding and ignoring Zero's distaste for vampires.

He often lies by omission to protect Zero and Yuki. He told Zero that the tattoo would prevent his awakening and later uses it to tame Zero to Yuki without telling either what he was doing.

He is however very proud and very protective of Zero and Yuki. When Zero made his declaration that he would kill all the purebloods. Kaien promised to stand in his way should he go after Yuki, no matter if it was right or wrong.

Plot Summary
Kaien has installed Yuki and Zero as the only guardians and ignores Zero's request for assistance. When Zero completely awakens as a vampire, he performs the ceremony to have Yuki tame Zero.

Kaien accompanies Yuki and Zero to the Hunter's Association's main headquarters in order to look up the records on Yuki's history, he states that it is due to his worry about the effect on Zero. Shortly after, Yuki accidently uncovers the fact that Kaien was once a vampire hunter, though Kaien ashamed for having killed vampires in the past and didn't want her to know, she states that he is her father and nothing has changed, Kaien is touched.

As Kaien is fully aware of who Kaname is to Yuki, he still questions what Kaname intends when making Yuki his lover.

When Yagari returns and they go and check on Zero following Yuki's change. Kaien admits to a disgusted Zero that he knew everything. With the vampires attacking the school, Kaien admits it is no longer peaceful. But as he swears to do no violence against vampires, it is not until the Hunters arrive that he along with Yagari go out and defend the Night Class. He goes up against the president of the hunter association and discovers the president has been partially taken over by drinking a power vampire's blood. He dispatches the president, but the Hunters take Kaien into custody for the disaster that has occured.

During the following year, Kaien has been in custody while Yagari acted as the chairman of the academy. Yagari and he convinced Zero to return to school, albeit allowing Zero the use of one of his apartments. Kaien is now acting as the President of the Hunter Association and returned back to the school as the Chairman. It is revealed that Yagari is actually the true head of the Hunters Association.

Kaien goes to Zero and reveals that the Hunter Association intend for Zero to become their president in the future and require him to attend the peace meeting. Kaien also tells Zero that he will stand between Yuki and Zero if necessary because he cares for both of them. Kaien attends the meeting with various other hunters, the meeting goes smoothly although Kaname interrupts it to inform Kaien that he will be able to see Yuki at the party, to which Kaien thanks him. Kaien expresses doubts over the way Kaname dealt with the former Vampire Council believing it too harsh and at risk of alienating the other vampires, in particular the other purebloods.

Kaien goes to see Yuki at the party, but expresses displeasure toward Kain over the difficulty in seeing her. His visit is delayed when they discover the body of a hunter. He gets to see Yuki when she walks into the room, but he finds is difficult to communicate that the pureblood has been bitten.

Trivia

 * Cross or Kurosu, means "black master." Kaien is a combination of kai, meaning "ashes", and en, meaning "village gate." The kanji for en is also used for Enma the ruler of the Underworld in Buddhist mythology.
 * When he was at his prime as a Vampire Hunter, Kaien Cross was known as the Vampire without Fangs.
 * Kaien enjoys wearing very odd clothing and can be spotted with oversized lion feet slippers and large colourful hats.