Saitama is an ordinary man who trained rigorously for three years, pushing his body to its absolute limits with a simple regimen of 100 push-ups, 100 sit-ups, 100 squats, and a 10-kilometer run every single day. This intense training gave him unimaginable power, allowing him to defeat any opponent with a single punch. However, his overwhelming strength has left him bored and unfulfilled, as no battle provides the thrill he craves. After registering with the Hero Association, Saitama meets Genos, a cyborg seeking revenge, who becomes his disciple. Together they face increasingly dangerous monsters and villains while Saitama searches for a worthy adversary who can withstand more than one punch.