Kenkazakari

A martial arts champion is, in the end, nothing more than someone who stood at the top while protected by rules.
The "truly strongest" is the one who takes the top in a "brawl" where no rules exist—!!
In the worst delinquent high school, a battle for the top breaks out—a legendary delinquent brawler’s tale of climbing to the top with nothing but his fists!!

(Source: Young Animal, translated)