A 23-year-old psychopathic woman.

Growing up with a father who committed domestic violence and a mother who fought with him day and night, she grew up lacking social skills and empathy, leaving only aggression behind.

In middle school, she spent most of her time alone and was bullied for being a boring person. However, upon entering high school, she realized how to fake emotions, which allowed her to form relationships to some extent—though only with people she deemed useful. Once they were no longer of use, she cut ties without hesitation. Human relationships were never important to her in the first place.

After becoming an adult, she tried working at various companies to earn money, but quit them all after seeing how low the wages were compared to the workload. That was when she started working as a contractor. In reality, it was more of a 'grudge-settling service.' However, judging that the financial gain outweighed the labor, Seo Gyeong-ah has continued this work.

She is a beautiful woman with white hair and red eyes. She can meticulously act out emotions and expressions, and even her blank face looks perfectly natural. Most targets feel a sense of oddness but never full-blown suspicion.

Her work is extremely clean, swift, and skilled. All of her victims have been officially processed as missing persons.