Full Metal Panic! Short Stories Volume 4 by Shouji Gatou

Having left his mercenary life behind for the peace and quiet of Tokyo, Sagara Sousuke is ready for the next chapter in his career... as a private investigator?! With his loyal(ish?) assistant Chidori Kaname at his side, he’ll apply his eagle’s eye to the murder of endangered snails at Jindai High, the potentially shady past of his overachieving student council president, and a new business that's moved in near the school—one that proports to indulge men’s greatest fantasies! Even when clues seem scattered to the four winds, Detective Sousuke is always on the case!