"I Shall Never Return" is a manga series that explores themes of identity, memory, and the consequences of one's choices. The narrative centers on a protagonist who finds themselves trapped in a mysterious, otherworldly realm after a sudden and unexplained event. This realm is populated by enigmatic beings and fragmented memories of the protagonist's past, creating a surreal and disorienting atmosphere. As the protagonist navigates this strange world, they encounter various characters who may be allies, adversaries, or manifestations of their own psyche. Each interaction reveals fragments of the protagonist's forgotten history, forcing them to confront unresolved guilt, regrets, and the weight of their decisions.

The plot unfolds through a series of episodic encounters, each delving deeper into the protagonist's past and the nature of the realm they inhabit. The boundaries between reality and illusion blur, as the protagonist struggles to discern what is genuine and what is a construct of their mind. Key characters include a guide figure who offers cryptic advice, a shadowy antagonist who seems to know more about the protagonist than they do themselves, and a recurring figure from the protagonist's past who symbolizes their deepest regrets. The story builds toward a climactic revelation about the protagonist's true identity and the reason they are trapped in this realm, culminating in a choice that will determine their ultimate fate—whether to remain in this liminal space or confront the reality they left behind. The narrative is marked by its introspective tone, intricate world-building, and a focus on the psychological and emotional struggles of its characters.