The story tells about the genius assistant Anna Mikami played by Hirose and the incompetent detective Naoki Fuma played by Sakurai, who team up to solve difficult cases. The two protagonists will start the story by searching for Anna's father who suddenly disappeared. Every time they solve an incident and find clues related to the disappearance, new mysteries will arise. When the key to all the mysteries is solved, the truth of "a certain incident" 20 years ago that was buried in the darkness will have a chance to be clarified...