"CATMAN" is an anime series that centers around a young man named Kaito, who discovers he possesses the ability to transform into a feline-human hybrid after a mysterious encounter with a supernatural entity. This transformation grants him enhanced agility, heightened senses, and retractable claws, but it also comes with a cost: he must navigate a hidden world of supernatural conflicts while concealing his dual identity from society.

The narrative begins with Kaito living an ordinary life in a bustling urban city, working a mundane job and struggling with feelings of isolation. His life takes a dramatic turn when he is attacked by a shadowy creature known as a "Nightstalker," a malevolent being that preys on humans. During the encounter, Kaito is saved by a enigmatic woman named Aya, who reveals herself to be a member of an ancient organization called the "Guardians." The Guardians are tasked with protecting humanity from supernatural threats, and Aya recruits Kaito after recognizing his latent potential.

As Kaito trains to control his newfound abilities, he learns about the existence of other hybrid beings like himself, each tied to different animal spirits. These hybrids, known as "Beastwalkers," are divided into factions, some aligned with the Guardians and others siding with the Nightstalkers. The conflict between these factions is rooted in a centuries-old struggle for dominance over the human world, with Kaito caught in the middle as a key figure due to his unique connection to the feline spirit.

Throughout the series, Kaito forms alliances with other Beastwalkers, including Ryo, a wolf hybrid with a fierce sense of justice, and Mei, a fox hybrid who specializes in espionage and deception. Together, they uncover a conspiracy involving a rogue faction of Beastwalkers seeking to unleash an ancient power that could tip the balance in favor of the Nightstalkers. Kaito's journey is marked by internal conflict as he grapples with his dual nature, the moral complexities of the supernatural war, and his growing feelings for Aya.

The plot escalates as Kaito and his allies confront increasingly powerful adversaries, culminating in a climactic battle that tests their resolve and unity. The series explores themes of identity, loyalty, and the blurred lines between humanity and monstrosity, all while maintaining a fast-paced narrative filled with action, intrigue, and moments of emotional depth. The story concludes with an open-ended resolution, leaving room for potential future developments in the world of "CATMAN."