The Hero is Beating Up the Bullies

The Hero, who defeated the Demon King and saved the world, is being summoned to a shitty delinquent school?! The otherworld Hero who was summoned to a den filled with the worst bullies ever, the 'Southern Suseong High'. Though the Hero doesn't use his powers against fellow humans, he begins to school these bullies after finding out about their 'demonic' nature...! Can the Hero defeat the bullies and return back to his world?