DDS

From Kokorodatabase

DDS stands for Dan Detective School. It is the only non-magical school in Japan where students are allowed to carry firearms. The school was founded by detective Dan Morihiko and is a place where students are trained to become detectives. The classes decend from A Class to D Class. The classes themselves are assigned various cases in addition to regular subjects and study sessions.

A special Q class was once created for a group of top minds in order to find an heir to take over the school in Dan's failing health.

The school itself is a reference/crossover to Tantei Gakuen Q.