"Boku ga Shinu dake no Hyakumonogatari" is a supernatural horror manga that revolves around a group of high school students who become entangled in a deadly game of storytelling. The narrative begins when the protagonist, a reserved and introverted student, is invited by a classmate to participate in a ritual known as the "Hyakumonogatari." This ritual involves gathering in a dimly lit room, lighting 100 candles, and taking turns telling ghost stories. After each story, a candle is extinguished, and as the room grows darker, the boundary between reality and the supernatural begins to blur.

As the ritual progresses, the students notice strange occurrences that defy explanation. The stories they tell start to manifest in the real world, and the participants find themselves facing the very horrors they described. The protagonist, initially skeptical, is forced to confront the terrifying reality that the ritual has unleashed malevolent forces. The group soon realizes that the only way to survive is to complete the ritual by telling all 100 stories, but the cost of doing so becomes increasingly dire.

The main characters include the protagonist, whose skepticism gradually gives way to fear and desperation as the supernatural events escalate. Another key figure is the classmate who initiated the ritual, whose motivations and knowledge about the Hyakumonogatari remain ambiguous. Other participants, each with their own fears and secrets, contribute to the growing tension as the stories they tell begin to reflect their innermost anxieties and guilt.

The plot intensifies as the students struggle to distinguish between the stories they are telling and the reality they are experiencing. The line between storyteller and victim becomes increasingly blurred, and the group must navigate a series of increasingly horrifying encounters with the supernatural. The stakes rise as they realize that the ritual may not only claim their lives but also trap their souls in a nightmarish limbo.

The manga explores themes of fear, guilt, and the power of storytelling, with each ghost story serving as a window into the characters' psyches. The narrative is structured around the progression of the ritual, with each chapter corresponding to a new story and a new horror. The tension builds steadily as the number of remaining candles dwindles, and the students are forced to confront the consequences of their participation in the Hyakumonogatari. The story culminates in a climactic confrontation with the forces unleashed by the ritual, leaving the survivors to grapple with the aftermath of their ordeal.