A real estate agent, Shinji Sawaguchi finds a fallen meteorite by accident. On the next day, his missing sister Shiori shows up for the first time in ten years. Shinji can't help being agitated by her sudden return. On the other hand, unusual events start happening in his life, and her threatening melody spreads in the town. Including Shinji's fiancé Maki, the development of characters centers around Shiori's mysterious presence felt. Shiori's identity is hidden, and Shinji gets involved in a peculiar situation.