Summary:

Hazuki Sataru and her siblings are forced to go through a very difficult and unpredictable surgery after they are attacked by vampires after they watched their parents being murdered. The surgery proves to be a success in Hazuki's case, but it does not work on her twin brother Kazuki, or either of her two younger siblings, Yuki and Airi, who turn into royal blooded vampires. Since the surgery worked on Hazuki, she became an element controller, changes her name to Loveless, and joins Rei's team of students who's goal is to protect regular humans of the world from vampires. Soon after, Hazuki is given the pleasure of leading her team for the first time on an assignment. But when she interrogates the only witness to the crimes she is trying to solve, she realizes who the criminals are. They are vampires. But not just any vampires, they are the two royal blood princes...her twin and younger brother. Hazuki is put in the position where she must either deny helping these humans who need help or facing her dangerous siblings for a fight to the death.