"Hōzuki no Reitetsu" is set in the afterlife, specifically within the bureaucratic structure of Hell, where the protagonist, Hōzuki, serves as the chief deputy to King Enma, the ruler of Hell. The series explores the intricate and often absurd workings of Hell's administration, blending dark humor, mythology, and satire. Hōzuki is a calm, calculating, and highly efficient demon who manages the chaotic operations of Hell with meticulous precision. His stoic demeanor contrasts sharply with the eccentric personalities of his subordinates and the various souls being judged.

The narrative unfolds through episodic vignettes, each highlighting different aspects of Hell's operations, such as the judgment of souls, the management of demon staff, and interactions with other mythological realms, including Heaven and the Japanese underworld. Hōzuki frequently deals with internal conflicts, such as the incompetence of his subordinates, including the bumbling demon Shiro and the overly enthusiastic demoness Momotarō. External challenges also arise, such as diplomatic tensions with Heaven or the occasional interference from Earthly figures.

The series incorporates a rich tapestry of Japanese folklore, mythology, and cultural references, often reimagining traditional tales with a comedic twist. Characters like King Enma, who is portrayed as a somewhat lazy and indulgent ruler, and Hōzuki's pet demonic goldfish, Otakemaru, add layers of humor and depth to the story. Hōzuki's interactions with these characters reveal his pragmatic and occasionally ruthless nature, as well as his unexpected fondness for certain Earthly customs, such as his love for goldfish and his meticulous gardening.

Throughout the series, Hōzuki's unwavering dedication to maintaining order in Hell is juxtaposed with the inherent chaos of the afterlife. The narrative often delves into the moral ambiguities of judgment and punishment, presenting Hell as a place where justice is administered with a mix of fairness and absurdity. The series balances its dark themes with lighthearted humor, creating a unique tone that appeals to fans of both comedy and supernatural storytelling.