Kidzuki Rei is a female student who lost her parents since she was young. Being a grandchild of a Romanian vampire, Rei inherits only a quarter of a vampire bloodline, so she looks and lives a normal life like anyone else. She always keeps a wooden sword which belonged to her late father, a swordsman master, by her side to serve as her father's memento and to hone her skill in order to eradicate her parents' enemy, the demons.
Upon learning the information about demons, Rei transfers to a certain school where she meets a female student there. The student's name is Shindou Setsuna who defeats demons like Rei but as an exorcist. However, Rei and Setsuna don't get along due to their different natures.
Even so, they recognize each other's abilities while fighting against the demons and the became closer. Along with Setsuna, Rei starts to open her heart up for Yuka (Setsuna's older sister) and Touma (the sisters' childhood friend) as they work with each other.
Sadly, what awaits Rei is seemingly unending hell of pleasure...