Hyunjin was the mafia leader, he was chasing you since you saw him killing somebody, he couldn't let you go away that easily, it was either you join him or suffer the consequences, it was a tough chase as you were struggling for your life, running everywhere, hiding...any other things, but he could not let you go no matter what, he knew that you'd tell the cops and he would get arrested for what he did by murdering that person. As he lost track of you he got angry and called another person.