Days of Wrath by Shin Jai-ho

6.20

Back in his high school days, Joon-Seok was bullied by Chang-Sik Because of this, Joon-Seok's high school days were like a nightmare. Now, Joon-Seok finds it difficult to live a normal life due to the bullying. Meanwhile, Chang-Sik, who has forgotten what he did to Jeon-Seok, lives a relatively happy life. He is about to marry Ji-Hee. Joon-Seok will pay him back for all the misery.