Bang Y/N was a girl who lives alone. Her family has split when she was younger after her parents decided to get a divorce. She had an older brother but his custody was given to her father, so she didn't have a chance to meet her brother after the divorce as her father moved to another city and decided to never contact them again. Her mom has died of heart disease a few years ago, which has broken her emotionally to the point that she stopped talking with literally everyone around her and even in her university, She had to move in with her mom's abusive sister. So, when was accepted in a company with a salary, which is more than enough to support her living, she decided to move to Seoul. She joined the company after a week of moving to Seoul city, everything was new here and she wished her mother still accompanied her in these difficult times. 'at least I'm free from the abusive woman. Thanks to heaven' she thought as she proceeded to her workplace. Everyone was trying to be nice to the new girl but she pushed all of their affection away, as she does usually after her loveable mother died. If anyone who is close to her during her childhood sees her now, they might not recognize her as she has changed her characters drastically. She used to be a cheerful young girl but right now all they could see was a gloomy, depressed and cold adult who seems like she doesn't need love in her life. There have been times when she wonders where her brother is? or what he is doing? or whether he still remembers her? But she never got an answer to those questions.  

As her day continued to move on the announcer in the news channel which was in television in her workplace gave some announcement "there have been mysterious deaths in Seoul city, 2 victims have been killed by wrapping their head in a plastic bag and were left to suffocate to death. Police are suspecting it to be a serial murder. People are asked to be careful of the strangers as the police continue to analyze the serial killer's attacking patter" The manager switched the

Television off and asked everyone to go back to their work. "Eyy.... a serial killer is roaming around? This is dangerous. We have to be careful" said y/n's colleague, Nayeon