Kaien Cross is the Headmaster and founder of Cross Academy. He is one of the strongest proponents of co-existence between humans and vampires, which is why he built the Academy. Adopted father of Yuki Kuran and Zero Kiryu, Kaien was the only person besides Kaname who was aware of Yuki’s true nature all along. Kaien was not originally such a strong proponent of peace. Born a hunter, he was for a long time considered to be the top Vampire Hunter in the Association. Retired for the past 16 years, he is now acting president of the Association along with Toga Yagari.
Current Age: 200+
Height: 184cm / 6′
Hair: Sandy Blond
Eyes: Brown
Race: Hunter
Position: Acting President of the Hunter’s Association
Weapon of Choice: Serrated swords
Other Jobs Held: Headmaster of Cross Academy, Parent
Hobbies: Cooking. Always makes elaborate dishes in his own “style”
Favorite Fashion: lots of layers
Taste in women: “She’s already married, so…”
Romantic Interest: Presumably Juri Kuran, although unspoken and knowingly unrequited
Family: Adopted daughter Yuki Kuran and adopted son Zero Kiryu, both living.
Known Friends or Associates: Toga Yagari, Juri Kuran, Haruka Kuran, Kaname Kuran, Yuki Kuran, Zero Kiryu, Isaya Shoutou, The Night Class, The Day Class… and a lot of other people. 
Known Enemies: Previous Association President, Rido Kuran, those who destroy the peace
Japanese Anime Voice Actor: Hozumi Goda
English Anime Voice Actor: Christopher Corey Smith
Cross has a cheerful, happy go-lucky, almost silly demeanor at times and dotes on Yuki (and Zero if he’d let him). This appears to be the persona he chooses, an expression of the optimism he holds for what he wants the world to be, but he is also capable of being both serious and deadly. He is fiercely protective of those he cares about and completely dedicated to the dream of co-existence.
In the past, his personality was drastically different. Before meeting Juri and Haruka Kuran, he was dark, angry and bitter, set on destroying as many vampires as he could. He was sometimes referred to as “the vampire without fangs” both because of his ruthless drive to hunt and because he was born with an unusually high concentration of vampire genetic material (something which all hunters possess in varying levels). His elevated level of vampire DNA resulted in him being a deadly fighter, having an aura which can sometimes feel like a vampire’s, and the fact that he stopped aging about 200 years ago. It also meant that the Association did not entirely trust him, concerned over the possibility that he might actually become a vampire or start craving blood, although he never did.
Meeting Juri Kuran eventually changed Kaien and his way of thinking. He retired as a hunter because he could no longer blindly accept the philosophy that “there was no sin in killing a vampire”. He remained in retirement until Rido and the Vampire Council’s collusion with the president of the Hunter’s Association led to both Rido and the Hunters attacking Cross Academy. Cross returned to his weapons in order to protect his students. The Night Class protected the Day Class from Rido’s vampires, and Cross protected the Night Class from the hunters. He defeated the President, who had been corrupted by Rido’s blood, and was incarcerated for a time as a result. Eventually he was freed and became acting president of the Association himself, with the assistance and co-leadership of Toga Yagari, who had stood by him in the fight for the Academy.
Because of his history, Cross can understand Zero’s current feelings and likely sees a lot of his younger self in the young hunter’s dark outlook. He loves both his adopted children and has told Zero that he will get between he and Yuki if one of them tries to harm the other.
All character histories reflect the manga-verse history rather than the anime-verse history on any points where the two conflict. Please note that they also contain major spoilers for current manga events.
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