No.

In the 15th episode of Itaewon Class, the prison boss secretly snitched on the villain in the show for money, causing the male protagonist Park Sae-ro to be seriously injured, and then refused to save him. It’s clear from this episode that the prison brother is the bad guy.

"Itaewon CLASS" is a TV series premiered by South Korea's JTBC TV station on January 31, 2020. It is directed by Kim Sun-yoon, written by Kwang-jin, and stars Park Seo-joon, Kim Da-mi and others. The drama is adapted from the webcomic of the same name, telling the story of Park Sae-ro, a young man with an upright personality who counterattacks in Itaewon to create a startup myth and takes revenge on the person who killed his father.