La temporada 1 de Detective School Q se estrenó el 15 de abril de 2003.

Q dreams of becoming a great detective, and what better way for the ninth grader to realise his dream than by enrolling into the Dan Detective School? Dan Detective School is Japan's First and only academy set up to groom the next Sherlock Holmes. And in "Class Q", a special class for the academy's brightest, student aren't just taught the basic know-how of detective work, but also the qualities that define a great detective, whether it's a curious mind, the ability to discern the smallest bit of evidence, or a devotion to righteousness. Kyu manages to qualify for Class Q, where he is joined by others: Megumi, Kintaro, Kazuma, and Ryu, who's highly regarded by Dan himself, but a mystery to others. Fellow rivals and friends in class, the fivesome will have to put their collective skills together if they are to solve, time and again, some of the most baffling cases involving everything from cold-blooded murder to restless ghosts. Will they make the grade?