The story takes place in two worlds where humans and magicians are irreconcilable. Humans live in a city called "The Cave", while magicians who worship the devil live in the "Magician's World". Magicians call humans "trash", and humans call magicians "monsters", and they hate each other. The magician uses his magic to create a "door" connecting the two worlds, and uses the humans in the "Cave" as experimental subjects to practice magic, and the cave dwellers who have suffered from it also rebel against the magician. The protagonist Kaiman is one of the victims of magic in the "Cave". Because of magic, Kaiman's head turned into a lizard and he lost all his memories. However, Kaiman's body has immunity to magic. In order to pursue his memory and restore his original appearance, Kaiman and his friend Nikaido began to hunt magicians. The killer from the "Magician's World" also appeared in the "Cave", and the fight was about to break out.