Mizuki Tono is a character from the fifteenth Detective Conan film, Quarter of Silence. She is a former resident of Kitanosawa, a village that was relocated due to a dam construction project. Mizuki works at a local lodge in the new Kitanosawa and is one of five childhood friends who reunite for the first time in eight years, the others being Keisuke Yamao, Fuyumi Tachihara, Takehiko Muto, and Shogo Hikawa. She had a troubled relationship with her younger sister, Natsuki Tono, who wanted to become a model. Eight years before the events of the film, Mizuki argued with Natsuki and, in a moment of frustration, shoved her. Natsuki stumbled into the road and was accidentally struck and killed by a car driven by Keisuke Yamao, who was fleeing from a jewelry store robbery. A young boy named Touma Tachihara witnessed the shove and was subsequently chased by Yamao, falling off a cliff and falling into an eight-year coma. Mizuki, terrified of being exposed as the one who inadvertently caused her sister's death, secretly became the sniper who pursued Touma after he awakened, hoping to silence him before his memories returned. She is shown to be a highly skilled markswoman, possessing a hunting license and using a rifle with precise accuracy, once shooting Yamao in the shoulder to save Conan and later disarming him. Despite this capability, she suffers from claustrophobia and a fear of dark, enclosed spaces, which prevents her from following the children into a cave. In terms of personality, she initially appears as a calm and collected member of the friend group, but her desperation and fear drive her to extreme actions. Her motivations are rooted in guilt and a desire to preserve the memory of her sister, whom she insists she never intended to kill. By the film's conclusion, Touma regains his memory and identifies her as the person who pushed Natsuki. Mizuki confesses her role in the accident and her subsequent attempts to prevent Touma from remembering, and she is taken into custody by the police. Takehiko Muto, who harbors strong romantic feelings for her, promises to wait for her release. Her relationship with Shogo Hikawa is also notable, as he had proposed to her in the past and was still in love with her at the time of his death. Mizuki's role in the story is that of a tragic antagonist, a character whose initial lapse in judgment leads to a chain of devastating events and who ultimately must face the consequences of her actions.