Ryuki Azuma is a rookie detective in the Investigation Department. She visits Nishihara Shu, a beautiful boy from Kitamizawa Shoes, with a 'footprint' from the crime scene. Although a pervert with a foot fetish, Shu's observational skills are as good as those of a forensic scientist. 'Footprints! Show them to me quickly!" While being played by the innocent Shu, Detective Azuma solves another mystery today... The key to the mystery is footprints, and this is the start of a unique mystery!