I’m a Student, Not a Young Master of the Underworld

[No System + not a goody-goody + one female lead + ruthless and decisive] Night always makes people feel a little excited. I'm not supposed to be a gangster's son, but somehow I am. I want to live a normal life. I don't know when this life will finally end. The girl I love points a gun at my head to avenge her family. My best friend is brutally murdered because of me. Don't challenge my authority, and don't test my strength. Because I'm a gangster's son!