The story takes place in a fantasy world and revolves around a 15-year-old girl named Pacifica Casull, who is the sister in a set of twins born to the royal family of a kingdom called Leinwan and then, literally, thrown away. The 5111th Grendel Prophecy predicts that she will be the "poison that will destroy the world" if she reaches her sixteenth birthday. To prevent this she is dropped off a cliff as an infant ("scrapped"). Believed to be dead, her survival remains no more than a rumour until she is already 15 years old.