Oz Vessalius, the heir to one of the duke houses, has just turned fifteen. His life is rich and carefree, shaded only by the constant absence of his father. At his coming‑of‑age ceremony, everything changes: for no discernible reason, he is thrown into the prison known as the Abyss, where he is rescued by a chain named Alice, the blood‑stained black rabbit. It remains unknown why he was cast into the Abyss, how Alice is involved, and what the organization Pandora seeks from him.