Zero Kiryu

Zero is Yuuki's childhood friend and student at Cross Academy. He is also a Guardian and likewise on the disciplinary committee. Zero has been living with Yuuki and Headmaster Cross, as the headmaster is his legal guardian. His family, a linear of vampire hunters, was murdered by a pureblood vampire when he was young. He harbors a deep hatred for vampires and claims to have taken on the role of Guardian to learn to hunt them better.