Claude is a vampire hunter with a witch's bloodline. He has been ostracized for his status and has chosen to join the Vampire Hunter School(Kirsten).One day，Claude receives a commission from Headmaster Mantis to travel to the Misty Forest in the north of the continent and investigate a mysterious vampire named Su. In the course of their adventure, they both grow up.Meanwhile,Headmistress Mantis is planning a crazy experiment for herself.