Itaewon Class Episode 1

 Park Sae Ro Yi (played by Park Seo Joon) swings his fist at Jang Geun Won (played by Ahn Bo Hyun) who bullies a classmate.

On his first day at school as a transfer student, Park Sae Ro Yi witnesses Jang Geun Won bullying a classmate by pouring milk over his head and slapping him. Sae Ro Yi gets mad at the sight of the other students pretending nothing is happening even as they are watching the bullying. So, he tries to stop the bullying. 

Later, Geun Won’s father, Jang Dae Hee (played by Yoo Jae Myung), and Sae Ro Yi ‘s father, Park Sung Yul (played by Son Hyun Joo), are both called to the school. Jang Dae Hee suggests that he will save Sae Ro Yi from getting expelled if he goes down on his knees and apologizes to Geun Won, but Sae Ro Yi refuses to apologize and speaks out his opinion, "If you do something wrong, it’s only right that you get punished. That's what my father taught me. My father also taught me that people should stick to their beliefs… I should get punished. But I can’t apologize to Jang Geun Won because I am not sorry at all." He chooses to get expelled in the end.

Soo Ah, who have received the assistance of Sae Ro Yi’s father for a long time through his support at the orphanage, discourages Sae Ro Yi, who can’t tolerate such injustice and is about to interfere. "You better get a grip of the situation before meddling in. That's Jang Geun Won, the son of your father’s boss." Despite Soo Ah’s advice, Sae Ro Yi interferes the bullying and throws a punch at Geun Won.

Consequently, Geun Won’s father Jang Dae Hee and Sae Ro Yi’s father Park Sung Yul are called to school because of the incidence between their sons. Jang Dae Hee offers to forgive Sae Ro Yi on the condition that he goes on his knees and apologizes to Geun Won, but Sae Ro Yi refuses the offer saying, "My father also taught me that people should stick to their beliefs… I should get punished. But I can’t apologize to Jang Geun Won because I am not sorry at all for what I did. I did what I believed to be right, which is also my father’s teaching and I want to continue to live by my belief in the future."

After listening his son’s remark and being pressed by his boss to apologize on behalf of his son or consider leaving the company, Park Sung Yul says, "I can’t believe I have a son like this. He is amazing. He is doing what he thinks is right and is willing to be responsible for his action. So, I have nothing more to say." Park Sung Yul decides to resign.

Park Sun Yul prepares to open a small pub with his son. One day, he gets hit by a car on his way home riding his motorcycle and passes away. The police comes to the funeral site and informs Sae Ro Yi that the suspect of the accident turned himself in and is requesting for a settlement. They present the case file for him to review, but Sae Ro Yi sinks to the floor in despair.

After the police leave, Soo Ah happens to see the pictures in the case file and notices that the car in the pictures belongs to Geun Won. Suspecting that Geun Won is involved in his father’s death, Sae Ro Yi searches for Geun Won and locates him in a hospital with a cast on his wrist. Sae Ro Yi confronts Geun Won and knocks him out for killing his father.