This is Yotsuya Town. It's an ordinary local town. But the detective agency that stands in the corner of the town is anything but ordinary! "I, Hikaru Hyakkiya! I'm a detective who runs an office in this town!" This detective has the power of monsters and is a detective of justice who brings evil monsters to justice! She has cute cat ears and proud boobs, but he's a bit of a screw-up. A new case comes to Hikaru's attention: a group of women have been found in the mountains in a state of disrepute, and the village at the foot of the mountain has been practicing a lewd custom since ancient times. Who is the culprit? No matter what the mystery, leave it to Yokiya Hikaru, the Specter Detective!