"ACCA: 13-Territory Inspection Dept." is set in the fictional kingdom of Dowa, a nation divided into 13 distinct territories, each with its own unique culture and governance. The kingdom is united under the oversight of ACCA, a powerful administrative organization responsible for maintaining order and ensuring the well-being of its citizens. The story centers on Jean Otus, a high-ranking officer in ACCA's Inspection Department, whose role involves auditing the various branches of ACCA across the territories. Jean is known for his calm demeanor, sharp observational skills, and a penchant for smoking cigarettes, which often serves as a subtle tool for his investigations.

Jean's life takes a turn when rumors of a potential coup d'état begin to circulate within the kingdom. These rumors suggest that certain factions within ACCA or the royal family may be plotting to overthrow the monarchy. As Jean travels across the territories for his routine inspections, he becomes increasingly aware of the political undercurrents and the possibility that he may be more deeply connected to the unfolding events than he initially realizes. His interactions with colleagues, friends, and local officials reveal layers of intrigue, loyalty, and betrayal, all of which contribute to the growing tension.

Key characters include Jean's close friend and confidant, Nino, who works as a photographer and harbors a mysterious past tied to the royal family. Nino's role becomes pivotal as the story progresses, shedding light on Jean's own origins and the broader political landscape. Other significant figures include Lotta, Jean's younger sister, who provides a grounding presence in his life, and Grossular, the head of ACCA's Inspection Department, who maintains a watchful eye on Jean's activities. The royal family, particularly Princess Schnee, also plays a crucial role in the narrative, as their decisions and secrets influence the kingdom's stability.

The plot unfolds through a series of episodic investigations, each set in a different territory, which gradually build toward a larger, interconnected story. Themes of political intrigue, loyalty, and identity are explored as Jean navigates the complexities of his role and the kingdom's fragile balance of power. The narrative maintains a deliberate pace, emphasizing character development and world-building, while the mystery surrounding the coup and Jean's true place in the kingdom's hierarchy keeps the tension alive.

"ACCA: 13-Territory Inspection Dept." blends elements of political drama, mystery, and slice-of-life storytelling, creating a nuanced and engaging narrative that delves into the intricacies of governance, personal relationships, and the consequences of power. The series stands out for its mature tone, intricate plot, and well-crafted characters, offering a thought-provoking exploration of a fictional world that feels both familiar and uniquely its own.