School bullies go above and beyond to be cruel.
Kingdom School: Absolute Evil (2021)
Related
Bullies target a female character. School bullies who are sadistic and cruel.
Guy seeks revenge against a sadistic dude who bullied him in high school.
South Korean films that show very real, very violent cases of school bullying that lead the victim to a quest for revenge.
Plots are very similar. Violence and school bullying lead one young man to use his smarts to outwit the bullies and get revenge.