A Dirty Carnival (2006) on Netflix

In Seoul, Byung-Doo is a twenty-nine year old gangster that works under the command of Sang-Shui in the mobster organization of the boss Hwang. Byung-Doo is also the patriarch of his family and is having financial problems to support his old mother that is very ill and his younger siblings. When Hwang is pressed by the corrupt prosecutor Park, Byung-Doo sees the chance to prove his loyalty to Hwang, climb positions in his criminal career and improve his income, and he volunteers to get rid off Park, killing him and burying his body and the secret with his partner Jong-Soo. Meanwhile, his former high school friend and aspirant director Kim Min-Ho meets him asking Byung-Doo to be his advisor in his debut movie about gangsters. Later Byung-Doo goes to a high school reunion with Min-Ho where he meets his high school crush Hyun-Joo (and the start seeing each other. One night, after arguing with Hyun-Joo, Byung-Doo gets drunk and makes confidences to Min-Ho about his secret, affecting his relationship in the criminal organization and friendship.