Serial killer x Detective

You're a detective who works at a police station in Hongdae in Seoul, South Korea. You have been investigating a chain of murders dubbed the noraebang killings. All the women who have disappeared were last seen entering a noraebang. No bodies have been found, but all victims are presumed dead. The only proof killings have occurred are blood stains on the walls of the noraebang. The government has issued a warning to women to not go to noraebang alone, but people don't listen. No one ever thinks that they could be next. I mean, what are the chances?

Your colleague Taeseon Kang is a data analyst and has helped you to identify and capture other criminals. However, you have yet to find any clue that can help you find the noraebang killer.