A group of Bald thugs use body armors to terrorize rich people. Sonic Speed, a hired ninja fights them. Unfortunately he meets with Saitama who is also a Bald.
Determined to get a little recognition, Saitama decides to become a pro hero, but first, he must pass the Hero Association tests and become a full-fledged member.
To remain on the "Hero" list Saitama has to show some activity in every week. Currently the City Z is defined as the 'ghost town'. Heroes are gathered together to find out whats going on.
Several Sea Folk appear and begin attacking citizens. They are easily defeated until The Deep Sea King appears and defeats many heroes including an S-Class.