Tantei Gakuen Q (2003)

Kyuu is your average boy with a knack for logic and reasoning. Desiring to become a detective, he finds out about the existence of the Dan Detective School (DDS); a famed school where students are allowed to bear arms. Together with Megu, a girl with photographic memory, the martial arts master Kinta, the genius programmer Kazuma and the mysterious Ryuu, Kyuu tackles many well planned out crimes, always seeking the truth.