Saitama Introduction Arc

The Saitama Introduction Arc is the very first arc in the series.

Plot
The arc begins with the monster Vaccine Man destroying a city and Saitama watching the event take place on TV deciding to intervene. As Vaccine Man is about to kill a child Saitama shows up to save that child and tells Vaccine Man that he is a hero for fun. As Vaccine Man transforms and prepares to attack Saitama he is defeated by Saitama in one punch and is killed, then Saitama get on the ground proclaiming that he was upset by how easy that was. We then flashback to when Saitama encounters Crabrante who is after a young child that drew nipples on his shell and Saitama kills Crabrante to save that child, afterwards he trains to become a hero. We then flash forward to Saitama shopping for food but is interrupted by the brain and brawn brothers who he swiftly defeats but accidentally destroys B-City in the process. While in his apartment he is attack by the subterranean who give him his first real fight in 3 years but as he is about to face off against their leader it is revealed to be a dream. When the real subterraneans invade they retreat after he instantly kills their leader.

Story Impact

 * This arc introduces Saitama's incredible power and his frustration with it.
 * It is revealed that credit for defeating Vaccine Man went to King who happen to be there at the time.
 * It is revealed the boy Saitama saved was the grandson of a wealthy man named Agoni who would found the Hero Association after this incident.