With Kageyama as her chauffeur, Reiko and her friends visit a crowded summer festival, where a cracked smartphone is discovered. Its owner was poisoned in his apartment, and he died wearing nothing but briefs. Three women the victim dated simultaneously on a matching app fail to match the height of a suspect seen exiting his residence, which leaves Reiko puzzled at the true culprit's identity.

Women of differing heights are spotted at the crime scene. Kageyama suspects that elevator shoes disguised the murderer's appearance. After learning that the victim had scammed several women via dating apps, Reiko inches closer to the truth. Later, a delivery man is found dead with an item belonging to his favorite VTuber, and it's discovered that the two even frequented the same hospital.

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?