Moon Seungchan is back in South Korea, and his father is trying to find out why he's chasing the killer. He tells his son that his brother went missing three months ago, and that the police are now looking into the case as a public one. The father says that he has accepted to study law at the university. He's shocked that his son is dead. He says that when his son was two, he won a gold medal in a national math competition and that was all he cared about. Now, he says, he has looked into his brother's family and found out that he was murdered by his father because he was jealous. He doesn't know why he killed his brother, but he does know that he is a serial killer.