The person who dropped it is a VTuber File 2 (S01E06)

Following the tragic fall of a delivery man, Reiko and Kyoichiro delve into his ties with the famous VTuber "Kuru Kuru-Chan," who has become the target of online accusations regarding the murder. Meanwhile, Kageyama lends a hand in investigating a mysterious figure seen planting bugs, unexplained untouched food deliveries, and clues left behind at the scene that could reveal the real perpetrator. Among the evidence, the victim's note states, "I've had enough of this world," raising questions about its meaning and relevance to the case.