Her name is Katherina Vakaria she is a 900,000 year old demon princess but she is a 17 year old Student at Cross Academy protecting the humans from the level E vampires who will eat humans like they are nothing. but there is some good vampires out there. no matter what you cant trust them. Zero tells her everyday that Vampires will hurt her but she knows they wont because they never have since she started school there and always there with the day class girls but not screaming for them but protecting them from the mob of girls.

Katherina is a shy girl but she keeps to herself most of the time. but when it comes to her duties she is very serious. when she hangs or talks to Zero she is a very happy girl even if she talks to her best friend.

She has no memory of much from her past from her age of 5 and younger. only one thing a vampire saving her and bringing her to the headmaster of Cross Academy. she saw him everyday till this day but he has disappeared for some reason and now Rina just does her duties with Zero protecting the day Class.