Sixth‑grade student Aya Tachibana, for her "successes" in school, is placed in a special class where she meets four boys—who later turn out to be the organizers of an amateur detective club. Each of them stands out from others by a particular trait: the brash and "poseur" Wakatake, the mysterious "expert in love affairs" Kuroki, the math genius Usugui, and simply a charming Kozuki—specialist in natural sciences. Aya, possessing extraordinary language‑learning abilities, becomes the fifth member of the club. And although the young detectives regularly quarrel, during joint work on another mysterious case they act together and use all their talents to the maximum!
