Headmaster Kaien Cross (黒主 灰閻理事長, Kurosu Kaien Rijichō?) is over 200 years old, the oldest and most powerful known Vampire Hunter. In spite of being a vampire hunter, Kaien maintained friendships with several pureblood vampire families. Kaien adopted Yuki and also took Zero into his home after they lost their families. Kaien retired as a vampire hunter and became the Headmaster of Cross Academy, he established the Day Class and Night Class with Kaname Kuran with dreams of promoting peace between humans and vampires. Kaien is an eccentric character who often provokes Zero and irritates other characters with his silly mannerisms, though he is a serious character when it comes to matters he cares about. He carries a hidden anti-vampire weapon in his cane which he uses to kill the President of the Hunters Association who had turned corrupt from drinking Rido Kuran's blood.