"No Guns Life" is set in a dystopian future where cybernetic enhancements, known as Extends, have become commonplace. The story centers on Juzo Inui, a former soldier turned Resolver—a private investigator specializing in cases involving Extends. Juzo is unique in that his head has been replaced with a gun, a modification that makes him a "Gun Slave Unit," a weaponized human. His past is shrouded in mystery, and he struggles with the ethical implications of his existence and the violence he is capable of.

The narrative begins when Juzo is approached by Mary Steinberg, a young woman seeking help to protect a boy named Tetsuro Arahabaki. Tetsuro is an experimental subject of Berühren, a powerful corporation that develops Extend technology. Berühren's experiments have left Tetsuro with the ability to control other Extends, making him a target for both the corporation and other factions vying for power. Juzo reluctantly takes on the case, driven by a sense of duty and a desire to uncover the truth about his own origins.

As the story progresses, Juzo and Tetsuro form an uneasy alliance, navigating a world rife with corporate espionage, political intrigue, and moral ambiguity. They encounter various adversaries, including other Gun Slave Units and agents of Berühren, each with their own agendas. The series delves into themes of identity, autonomy, and the consequences of technological advancement, as Juzo grapples with his own humanity and the ethical dilemmas posed by his existence.

Supporting characters include Olivia, a skilled hacker and Juzo's associate, who provides crucial assistance in their investigations. Pepper, a former colleague of Juzo's, also plays a significant role, offering insights into Juzo's past and the broader implications of the Extend technology. The series balances action-packed sequences with moments of introspection, exploring the personal struggles of its characters against the backdrop of a society grappling with the ramifications of its technological progress.

The plot is driven by a series of interconnected cases, each revealing more about the world and its inhabitants. As Juzo and Tetsuro uncover the truth about Berühren's experiments, they are drawn deeper into a web of conspiracy that challenges their understanding of right and wrong. The series maintains a steady pace, blending episodic investigations with an overarching narrative that builds toward a climactic confrontation with the forces that seek to control both Juzo and Tetsuro.