Life gets pretty boring when you can beat the snot out of any villain with just one punch. Nothing about Saitama passes the eyeball test when it comes to superheroes, from his lifeless expression to his bald head to his unimpressive physique. However, this average-looking guy has a not-so-average problem-he just can't seem to find an opponent strong enough to take on! Monster Association big shots are taking out S-class heroes one after another... That is, until the strongest man alive, King, rises to confront this crisis. Though the monsters are seething with malice, King appears cool and composed. But can his cool act defuse the dire situation?!