According to Saitama, he achieved his god-like strength through a strict training regimen: 100 push-ups, 100 sit-ups, 100 squats, and a 10km run every single day for three years (without using air conditioning).

However, in-universe theories suggest he broke his "limiter"—the natural growth limit placed on living beings—through sheer willpower and effort.

The S-Class is the highest rank in the Hero Association, reserved for heroes with insane, superhuman capabilities.

Originally, the association only had classes A, B, and C, but they created the S-Class to accommodate individuals whose power defied standard logic (like Tatsumaki, King, and Genos) and who could single-handedly defeat Demon or Dragon level threats.

It is a unique blend of action, satire, and comedy.

While the premise of a hero defeating everyone in one punch is a gag on shonen tropes, the series features serious character development, high-stakes battles (for characters other than Saitama), and genuine emotional moments. It parodies superhero genres while also being a top-tier example of one.

Blast is the Rank 1 S-Class hero and the most powerful hero in the Association.

He is an enigmatic figure who only appears during god-level threats. Unlike other heroes, he operates independently, traveling dimensions to collect mysterious cubes and fight a cosmic entity known as "God."

The Webcomic (drawn by ONE) is the original source material with a rougher art style. The Manga (drawn by Yusuke Murata) is a high-quality adaptation that expands on the story, adds new arcs (like the Super Fight Tournament), and features some of the best artwork in the industry. The manga is considered the definitive version for most fans, though the webcomic is further ahead in the plot.