Saitama may be a hero who only became a hero for fun. After three years of “special training,” he’s become so strong that he’s practically invincible. In fact, he’s too strong even his mightiest opponents are taken out with one punch. Now, the good seer Madame Shibabawa’s prediction about the world being doomed seems to be coming true because the frequency of monster incidents escalates. Alongside Genos, his faithful disciple, Saitama begins his official hero duties as a member of the Hero Association, while Garou, a person utterly fascinated by monsters, makes his appearance.