The “Seven Deadly Sins”—a group of evil knights who conspired to overthrow the kingdom of Britannia—were said to have been eradicated by the Holy Knights, although some claim that they still live. Ten years later, the Holy Knights have staged a Coup d'état and assassinated the king, becoming the new, tyrannical rulers of the kingdom. Elizabeth, the king's only daughter, sets out on a journey to find the “Seven Deadly Sins,” and to enlist their help in taking back the kingdom.
The story revolves around Kaiman, who does not remember who he was before he was transfigured by a Magic user. This transformation left him with a reptile's head, and a desire to find out the truth about who he really is. Accompanied by Nikaido, his female companion, he tracks down Magic Users in "The Hole" and unceremoniously chomps down on their head, hoping to find out who it was that put him in this state. One by one, they witness this "second man" inside the head of Kaiman, and after pulling them back out of his mouth he asks them all a question... "What did the guy inside my head say?"