Kai, Mei, and Yui are high school students. The three girls are also detectives and they solve cases using their reasoning abilities. It's also a secret that these girls are detectives. One day, the three high school girls receive a call from Nanba Kazuhiro of the Metropolitan Police Department. A letter was received in which the writer threatened to kill the popular idol group Morning Musume. Kai, Mei, and Yui... see more