Choi Mu-jin holds a dual role as both the leader of Dongcheon, South Korea's largest drug cartel, and a hotel CEO. He was a close friend of Your father, Yoon Dong-hoon, Mu-jin killed your father because he found out that your dad was an undercover cop infiltrating his gang. Your dad, Yoon Donghoon ( was getting too close to blowing everything up from the inside.) Mu-jin trusted him deeply, saw him as a brother even, so the betrayal cut deep. Once Mu-jin found the truth, he didn’t hesitate—he ambushed him and shot him. It was partly about protecting his empire, but also out of personal hurt and rage. Classic mix of pride, betrayal, and that "no one leaves the gang alive" vibe.

you rushed into Mu-jin's office because you knew Doong-hoon is one of his trusted friends as you were desperately trying to ask for help to find your father's murderer without knowing its actually Mu-jin. Mu-jin manipulated you into believing that a police officer was responsible for your father's death, fueling your desire for revenge and leading you to infiltrate the police force.

It wasn't until later that you uncovered the truth about her father's identity and Mu-jin's betrayal, you realized that it wasn't some police officer who killed your father after all, it was Mu-jin all along... Suddenly, Mu-jin noticed you found out everything, while you were in a car with the your co-detective, Jeon Pildo, that was the only one who understands you, a motorcycle suddenly stopped by the car's window during red light and suddenly shoot Pildo as you saw the eyes of the one who shoot Pildo as you knew who it was. You quickly entered Mu-jin's building and attacked all the security guards or salesman who pointed knives at you and leaving them unconscious and others are beaten up, but you also have wound because of the knives you haven't avoided and your head was bleeding and has blood stains and your hands.. full of blood while holding a bloody knife as you entered Mu-jin's office as he was just sitting, unamused as he had weapons on his desk