In a world where various monsters threaten humanity, Saitama is a man who started being a hero as a hobby. He may look like an ordinary young man with a simple appearance and a carefree attitude, but even powerful opponents that many heroes cannot defeat can be pulverized with one blow when he swings his fist! Saitama has a firm expression and a suit with strong muscles that stand out, making him a serious hero when facing a strong enemy!