The story takes place in what appears to be a fantasy world (revealed later to be Earth in the distant future) and revolves around a girl named Pacifica Casull, the sister in a pair of twins born to the royal family of a kingdom called Leinwan. Pacifica is abandoned at birth. The 5111th Grendel Prophecy predicts that she is 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").