"Mayonaka no Kaitō, Mangetsu yori Arawaru" centers on a mysterious thief known as Mangetsu, who operates under the cover of night, stealing valuable items from the wealthy and corrupt. The story is set in a world where the line between justice and crime blurs, as Mangetsu’s actions are driven by a personal code of ethics rather than greed. The protagonist, a high school student named Akira, leads a double life: by day, he is an ordinary student, but by night, he transforms into Mangetsu, using his intelligence, agility, and a carefully crafted persona to execute his heists.

Akira’s motivations stem from a desire to expose the hypocrisy and corruption of the elite, targeting those who exploit their power for personal gain. His heists are meticulously planned, often involving elaborate schemes and disguises to outwit both his targets and the authorities. The narrative explores the moral ambiguity of his actions, as he justifies his crimes by redistributing wealth to those in need or exposing the misdeeds of his victims.

The series introduces a cast of supporting characters, including a determined detective, Rina, who is tasked with capturing Mangetsu. Rina’s pursuit is driven by a sense of justice, but as she delves deeper into the case, she begins to question the true nature of Mangetsu’s motives. Their dynamic evolves into a cat-and-mouse game, with moments of tension and mutual respect. Additionally, Akira’s classmates and friends remain unaware of his secret identity, adding layers of complexity to his interactions and the risks he faces.

The plot is structured around episodic heists, each targeting a different corrupt individual or organization, while also weaving in an overarching narrative that delves into Akira’s past and the events that shaped his transformation into Mangetsu. Themes of justice, morality, and the consequences of one’s actions are central to the story, as Akira grapples with the impact of his double life on himself and those around him. The series balances action, suspense, and character development, creating a compelling exploration of its central premise.