Boss in School

Seth Kwon was a born fighter. But due to his promise with his mother, he decides to stop fighting, even in self-defense… Everything changes when his father dies and leaves him with a single message: “stop getting your ass kicked”.

Season 2 https://mangakik.com/manga/boss-in-school-the-beginning/

Season 3 https://mangakik.com/manga/boss-in-school-season-3/