This is the story of unusual creatures called "monsters," and a royal family who rules over them all. One member of the royal family, Hime, is embroiled in a battle to become the new ruler. Then there's Hiro, a boy who gains immortality from Hime's blood. Hiro finds himself entangled in Hime's fight for the throne, and discovers the world of monsters, the royal family secrets, and mysteries behind the fight to claim the throne. There is no telling how deep this abyss is!