"Kuchisake Onna Densetsu" is a horror manga that draws inspiration from the Japanese urban legend of the Kuchisake-onna, or "Slit-Mouthed Woman." The narrative centers around a cursed entity, a woman with a grotesquely disfigured mouth, who terrorizes a small town. The story begins with the sudden reappearance of the Kuchisake-onna, who had been dormant for years. Her presence is marked by a series of gruesome murders, each victim found with their mouths slit from ear to ear, mirroring her own disfigurement. The legend dictates that she approaches her victims, often children or teenagers, and asks, "Am I beautiful?" If they answer "no," she kills them instantly. If they answer "yes," she reveals her mutilated face and repeats the question. Any response after this leads to their death, unless they can distract or outwit her.

The protagonist, a high school student named Aya, becomes entangled in the curse when her classmates begin to fall victim to the Kuchisake-onna. Aya’s younger brother, Takuya, is also targeted, forcing her to confront the entity directly. As the story progresses, Aya uncovers the origins of the curse, tracing it back to a tragic incident involving a woman who was brutally disfigured by her jealous husband. The woman’s spirit, consumed by rage and sorrow, became the Kuchisake-onna, bound to wander and exact vengeance. Aya learns that the curse can only be broken by uncovering the truth behind the woman’s death and performing a specific ritual.

The manga delves into themes of fear, vengeance, and the consequences of unchecked jealousy and violence. Aya’s journey is fraught with tension as she navigates the supernatural threat while grappling with her own fears and vulnerabilities. The Kuchisake-onna is portrayed as both a terrifying antagonist and a tragic figure, her actions driven by the pain of her past. The narrative builds toward a climactic confrontation where Aya must use her wits and courage to break the curse and save her brother, while also offering a form of closure to the tormented spirit. The story concludes with the town returning to normalcy, though the lingering presence of the legend serves as a reminder of the thin veil between the living and the dead.