Akutsu Eiji is a newspaper reporter. He is working on unsolved case that took place 30 years ago. The case involved a group of people extorting several companies for money. The group sent cassette tapes to the companies. Akutsu Eiji comes across a mysterious cassette tape. Meanwhile, Sone Toshiya lives in Kyoto and runs a tailor shop. He discovers a cassette tape among his late father's possessions. He plays the cassette tape and hears his voice from his childhood days. (Source: AsianWiki) ~~ Adapted from the novel "The Voice of Sin" (罪の声) by Shiota Takeshi (塩田武士), which in turn was inspired by the extortion case "Glico Morinaga case" (グリコ・森永事件).