Garou calls himself a monster, and the heroes he attacks have been unable to stop him. Once the finest disciple of the legendary martial artist Silverfang, he now targets the Hero Association for reasons that remain unclear. His assault begins at a meeting with hoodlums whom the Association's executives hope to recruit, a desperate measure prompted by the growing number of monsters stretching their resources.
Meanwhile, Saitama has settled back into his ordinary routine in Z-City after defeating Boros and his army, unaware that monster appearances are increasing. Intrigued by Garou and eager for money, he enters a martial arts tournament. While the competition gets underway and Garou's attacks continue, another threat emerges with consequences for the entire human world. Whether it is the catastrophe foretold by the great seer Madame Shibabawa remains uncertain.
