"Not Lives" is a manga series that blends elements of psychological thriller, action, and survival game genres. The narrative centers around a deadly online game called "Not Lives," which traps its players in a high-stakes virtual world where failure results in real-world death. The game is orchestrated by a mysterious entity known as the Game Master, who enforces strict rules and manipulates the players' fates.

The protagonist, Reiichi Hiraga, is a high school student who becomes entangled in the game after his sister, Rina, is killed while playing it. Determined to uncover the truth behind her death and the game's origins, Reiichi enters "Not Lives" alongside other players, each with their own motivations and backstories. The game assigns players unique roles, such as "Hero," "Villain," or "Neutral," which dictate their objectives and interactions within the game. These roles are not fixed and can change based on the players' actions, adding layers of unpredictability and tension.

As Reiichi progresses through the game, he encounters a diverse cast of characters, including allies and adversaries. Among them is Akira, a skilled player with a mysterious past, and Yui, a fellow student who becomes a key ally. The dynamics between the characters are shaped by their roles, personal goals, and the constant threat of elimination. The game's challenges are designed to test the players' morality, resolve, and willingness to sacrifice others for survival.

The plot unfolds through a series of increasingly complex and dangerous stages, each requiring strategic thinking and cooperation—or betrayal—to advance. The Game Master frequently introduces twists and obstacles, forcing the players to adapt and confront their deepest fears and desires. The stakes escalate as Reiichi uncovers darker secrets about the game's purpose and the true nature of the Game Master, leading to a climactic confrontation that challenges his understanding of reality and the boundaries between the virtual and real worlds.

Throughout the series, themes of trust, identity, and the consequences of one's choices are explored, with the characters' actions often blurring the line between right and wrong. The narrative maintains a tense and suspenseful atmosphere, driven by the constant threat of death and the psychological toll of the game. "Not Lives" offers a gripping exploration of survival and human nature within the framework of a high-stakes virtual competition.