Horrible title. There is almost no detectiving going on here, and they are hardly a club. They are girls, though. This OVA sucks, kind of like a store brand version of Project A-ko, complete with an obsessive lesbian (literally attaching herself to the main girl at nearly all times) and overly goofy action. Really, it's got its moments, but the animation is terrible, and it's simultaneously too long for how thin the story and characters are, and too short for how its silly mystery action plot needed to be. Kind of the case for a lot of these 80s/90s anime OVAs.