Saitama obtained his power through a rather unconventional way. He simply trained non-stop, doing mundane exercises like push-ups, sit-ups, and running. This extreme dedication transformed him into the powerful being he is now. It's a simple yet unique origin story.
The Wandering Emperor and Saitama were both given great power in One Punch Superman, but the source was different.
The Wandering Emperor's power came from a mysterious existence known as the " Will of the Universe." This existence had once given the Wandering Emperor superhuman strength, allowing him to easily defeat ordinary heroes. However, as the Wandering Emperor continued to grow, he gradually discovered the true source of his strength. He realized that his power did not come from the will of the universe, but from his own will and determination.
In contrast, Saitama's power came from the gods. In one punch, the gods bestowed Saitama with great power, making her invincible. Although Saitama was able to increase his strength through hard work and training, the true source of his strength was still the gods.
It should be noted that although the Wandering Emperor and Saitama had different sources of power, they were both very powerful heroes who could bring great contributions to this world.
Saitama's rank in the web comic is sort of unconventional. His strength is off the charts, making it difficult to slot him into a specific rank. You could say he's in a league of his own, far above the typical rankings.
Well, Saitama All Fiction could potentially refer to a fan - created idea that emphasizes Saitama's ability to be above all the normal rules of the fictional One Punch Man universe. For example, his strength is so overwhelming that it's like he exists in a realm of his own, where the typical limitations of the story don't really apply to him. He can defeat any foe with just one punch, and this 'All Fiction' concept might be an attempt to explain how and why he's so powerful in such a ridiculous way.