Part 3: "Detective S"

University student Imai (Suga Kenta) is invited by his classmate Kajiwara (Furukawa Takeshi) to collaborate on a report on criminal psychology. The two begin playing detective to uncover the modus operandi of the crime, using the case of an idol being stalked online as their theme. Meanwhile, Riricchi, the idol they are playing detective with, receives a creepy wedding cake...