Yuu Asakura is a Japanese teenager with brown hair cut to ear length and gray or blue eyes. Initially a mild-mannered, unremarkable university student with a friendly disposition, his life shifts irrevocably upon discovering a duffel bag containing money, a handgun, and assassination instructions. Though terrified at first, handling the weapon triggers a profound psychological shift. The gun possesses supernatural or cursed properties, amplifying violent impulses and eroding the wielder's morality, driving them toward madness and criminality. His family background involves being the stepson of Misako Asakura, a widow his father married. After his father's death, they formed a blended household with Misako's biological daughter, Masami. The gun's discovery corrupts these dynamics, leading to coercive sexual encounters initiated by Misako, who rationalizes their relationship as she is not his biological mother. These encounters escalate to intercourse under duress, including at gunpoint. Under the gun's influence, Yuu accepts the assassination mission, entering a world of violence, criminal activity, and nonstop sexual encounters. His personality transforms from timid to dominant and amoral; he leverages the gun's power to manipulate others, becoming capable of extreme acts like armed robbery, rape, and murder, depending on narrative choices. This corruption manifests variably: he might sexually assault classmates, aid in assassinations, betray allies, or frame innocents. The gun's original owner, Ichihara Masaki—once a normal college student similarly warped by its power into remorseless criminality—relentlessly pursues Yuu to reclaim it, resulting in violent confrontations. His interactions further illustrate his degradation. He encounters Angel, a professional assassin who enlists his help to kill an arms dealer. Depending on choices, Yuu either assists her or intervenes to save the target's daughter, Nami Kumagai. In one path, he participates in breaking Nami's mind with drugs after her father's murder and later rapes her; alternatively, he may develop a romantic attachment to her following a rescue. His relationship with stepsister Masami also varies: in some conclusions, their bond evolves romantically after surviving crisis, while in others, he sexually exploits her. Yuu's arc encompasses multiple possible resolutions: dying in police confrontations, becoming a full-time hitman accepting new missions, impregnating a victim after rape, or achieving fleeting stability with Masami. A recurring theme is the gun's enduring psychological hold; its influence may persist even when separated from the weapon.