ONA
Description
Kaiman is the main protagonist of the story, a human originally from a grim, industrial city known as the Hole. Not his original name, Kaiman was christened by his best friend, Nikaido, after she found him suffering from total amnesia. His most striking feature is his reptile-like head, which is the result of a curse from a magic user. This transformation is the driving force of his existence, as he is on a single-minded quest to find the sorcerer responsible and force them to change him back. His body remains powerfully built, standing an imposing 216 centimeters tall, and his appearance evolves in the narrative from a lankier frame to a much more muscular, broad-shouldered physique. He typically wears a modified gas mask to hide his face in public.

On the surface, Kaiman often comes across as arrogant, lazy, and easily distracted, with a violent and stubborn streak that makes him quick to resort to bloodshed. He is prone to slacking off at his various part-time jobs and is perpetually short on money. However, this rough exterior conceals a more caring nature, most evident in his deep, unwavering loyalty to Nikaido. He holds a profound hatred for magic users, viewing them as scum who prey on the people of the Hole. He shows them no mercy, killing them without remorse after his interrogation. Despite his brutality, he is not entirely heartless, as he can be momentarily moved by the pitiable state of certain enemies and is terrified of ghosts, a fear he vehemently denies.

Kaiman's primary motivation is to find the magic user who cursed him so he can regain his human face. His secondary, yet equally important, desires are to eat Nikaido's homemade gyoza dumplings and to have more money, in that order. To identify his target, he employs a unique and gruesome method. He clamps his jaws around the head of every magic user he encounters, which allows a mysterious, cross-eyed little man living in the back of his throat to examine them. After pulling the victim out, Kaiman asks them, What did the guy inside my head say? If the answer is not the one, he immediately kills them. This practice has earned him the fearsome moniker of the Magician Killer.

Within the story, Kaiman functions as a relentless force of chaos, hunting magic users in the Hole and drawing the ire of powerful figures in the sorcerers' world, most notably the gangster boss En. His actions are the catalyst for much of the conflict, as En sends his elite cleaners, the vivisectionist Shin and the healer Noi, to eliminate the lizard-headed menace. Kaiman's role often pits him against these and other foes, leading to brutal and bloody confrontations that reveal more about the world and his own mysterious nature.

The most significant relationship in Kaiman's life is with Nikaido, his sole companion and the proprietor of the Hungry Bug restaurant. She is his protector, partner in hunting magic users, and the cook who indulges his insatiable appetite for gyoza. Their bond is unshakable, rooted in a promise and a shared history that Kaiman cannot fully remember. He is fiercely protective of her, and she of him, forming a formidable duo. Other key relationships are largely antagonistic, such as his deadly rivalry with the cleaner Shin and the vengeful Fujita, a low-level magic user whose friend Kaiman killed. He also has a casual, often annoying, association with his employer, Dr. Vaux at the Hole's hospital for magic victims.

Kaiman's development is tied to the gradual unraveling of his amnesiac past. He is plagued by constant nightmares of his own death and a mysterious figure walking away from his corpse. As the story progresses, clues emerge that his identity is deeply connected to a powerful and enigmatic figure known as Ai Coleman, suggesting he may be a split personality of this sorcerer from the magic users' world. His understanding of his friend Nikaido also deepens when he learns she is secretly a magic user herself, a fact he must reconcile with his hatred for her kind. His resolve strengthens not just to change his head, but to understand who he truly is.

Regarding his abilities, Kaiman possesses several notable traits. He is completely immune to the effects of magic smoke, which gives him a tremendous advantage over the sorcerers he hunts. He is an exceptionally skilled and brutal close-quarters combatant, adept with combat knives and possessing superhuman physical strength capable of overpowering most enemies. Most remarkably, he has shown an advanced regenerative ability, able to regrow his entire head after it was severed by Shin, a process that takes only a few days. His resilience and tenacity in battle, shrugging off injuries that would be fatal to normal humans, make him an incredibly difficult opponent to kill.