Caiman, an amnesiac inhabitant of the dystopian Hole, bears a reptilian head due to a sorcerer's curse. Uniquely immune to all magic stemming from his chaotic creation involving fused entities and magical events, he hunts sorcerers indiscriminately to find the one responsible. He bites their heads to consult "the man inside his mouth" – his former friend Risu, trapped within – demanding, "What did the guy inside my mouth say?" Before executing those he deems culpable, the phrase "You are not the one" seals their fate. This body originally belonged to Ai Coleman, successively dominated by personalities: first Aikawa, then Kai (homicidal leader of the Cross-Eyes), and finally Caiman. Fleeing to the Hole to escape a curse pursuing him for murdering Risu, Kai was decapitated. In his final moments, Kai activated Ebisu's Reptile Transformation smoke flask, triggering the growth of a new reptilian head and trapping the pursuing curse inside the body. This erased all memories, forging the amnesiac identity Nikaido named Caiman after discovering his transformed body. Despite his violent profession as a "Magician Killer," Caiman displays a lazy, arrogant demeanor yet exhibits genuine kindness and loyalty, especially towards Nikaido. His core motivations are restoring his original head, eating gyoza, and acquiring money, in that order. He kills sorcerers without remorse, viewing them as universally malevolent, though he spares those who refrain from harming humans, like a benevolent fortune-teller in the Hole. Caiman works, often slacking off, at Dr. Vaux's hospital for magic victims. His reputation draws the attention of En, a powerful sorcerer crime lord who sends enforcers like Shin and Noi to eliminate him. Shin decapitates Caiman, revealing his regenerative ability: a new head regrows within days while the severed head is preserved. This preserved head later resurrects independently as Risu. Caiman suffers nightmares hinting at his fragmented past, including flashes of Risu and surgical devil tumor extraction. These dreams intensify during his journey to the Sorcerer World with Nikaido and Professor Kasukabe, where he attempts indiscriminate slaughter to find his curser and recalls the name "Risu." Investigations reveal the "man inside his mouth" sought Kai, not the curser. The body's history includes Kai's role as Cross-Eyes leader, who nearly destroyed En's family years prior. During the climax, Caiman temporarily gains immense magical power from devils, manifested as a wish-granting gyoza capable of diverse offensive and defensive abilities. Despite earlier desires for normality, he ultimately accepts his reptilian form, declining restoration of his original head. His physical design evolves from a lanky, elongated reptile to a burlier, muscular build with a shorter snout, though his red cross-shaped eye markings remain consistent. After losing his head again mid-series, his body is briefly controlled by the resurgent Aikawa before his return.