The person who dropped it is a VTuber File 2

Overview

After a delivery man falls to his death, Reiko and Kyoichiro investigate his connection to popular VTuber "Kuru Kuru-Chan," who is blamed for the murder by fans online. Kageyama assists in analyzing a mystery figure planting bugs, untouched food deliveries, and hints to the true culprit left at the crime scene. The victim leaves a note reading, "I've had enough of this world," but in what context?