In Karneval, Nai is searching for the precious friend he has lost when he is captured by a beautiful woman whose charm is matched only by her appetite for human flesh. At the same time, Gareki, a sharp-minded thief, is sneaking through her luxurious home to carry out a robbery. After Gareki creates a distraction, he helps Nai escape, but the two are caught when the woman returns and reveals her monstrous form, forcing them to flee.
As the two run for their lives, Karneval brings them into the orbit of Circus, a government defense agency that handles criminal cases beyond the police's reach and protects civilians from varuga, terrifying creatures that feed on human flesh. Hoping Circus can lead Nai to his missing friend, they decide to join the organization and travel alongside its members. Their journey puts them face to face with relentless varuga attacks while they begin to uncover the secrets surrounding Kafka, a shadowy organization whose influence reaches deeper than they first imagine. Between danger, shifting loyalties, and the search for answers, Nai and Gareki are pulled into a world where every encounter seems to hide another layer of danger.
