"Executioner and Her Way of Life" is set in a world where individuals from another dimension, known as "Lost Ones," occasionally appear, often possessing dangerous powers that can destabilize the balance of the world. These Lost Ones are typically executed to prevent catastrophic consequences. The story centers on Menou, a young executioner tasked with eliminating Lost Ones. Menou is a calm and methodical individual, trained by the Faust, a powerful religious organization that governs the world and enforces the elimination of Lost Ones.

The narrative takes a significant turn when Menou encounters Akari, a Lost One with an unusual ability: she cannot be killed. Akari's power of immortality complicates Menou's mission, as traditional methods of execution fail. Despite her initial resolve, Menou finds herself forming a complex relationship with Akari, who is cheerful, optimistic, and deeply attached to Menou. This dynamic forces Menou to confront her own beliefs and the rigid doctrines of the Faust.

As the story progresses, Menou and Akari embark on a journey that reveals deeper layers of the world's political and magical systems. The Faust's true motives and the origins of the Lost Ones come into question, with Akari's presence serving as a catalyst for uncovering hidden truths. The narrative explores themes of morality, duty, and the consequences of wielding power, as Menou grapples with her role as an executioner and her growing attachment to Akari.

Supporting characters, such as Momo, Menou's loyal and protective assistant, and other members of the Faust, add depth to the story, highlighting the tensions within the organization and the broader societal implications of their actions. The interplay between Menou's stoic professionalism and Akari's unwavering affection creates a compelling emotional core, driving the narrative forward as they navigate a world filled with intrigue, danger, and moral ambiguity. The series blends action, mystery, and philosophical inquiry, offering a nuanced exploration of its central characters and the world they inhabit.