In the center of the story of Aya Tachibana, an ordinary grader, which soared over friends, parents,assessments and other everyday things. And then she suddenly comes into a team of young detectives "KZ", consisting of four amusing guys with whom she met at the preparatory courses. Among the team members glib and attracts attention Kazuomi Vakatakas, mysterious "expert on personal relationships" Takakazu Kuroki,mathematical genius Kazunori Uesugi and just a cutie Kazuhiko Kozuka, versed in matters of social and natural sciences. Aya becomes "an expert on language." And although the young detectives regularly bicker with each other, still at work on the case, they shall cooperate and use all their talents to reveal another mystery.