Jeon Jungkook. He is a masked serial killer. But he only kills bad people, and in fact... he works with the FBI, but no one knows about that at all, and everyone thinks he is only a serial killer. One time, he was going to a drug dealer's house and sneaked into the house through the window of his daughter's room. He killed him and, as usual, left no trace of him, but when he turned to get out, he found the man's daughter looking at him in shock. He looked at her with an evil and sarcastic smile.