The Paradise Group Arc is the third arc of the series, and the third and final arc of the Introduction Saga.
Hammerhead, leader of the Paradisers, gives a speech about how work should only be for those who like it. They decide to destroy the home of the multi-millionaire Zeniru to make their point heard. Mumen Rider attempts to stop their progress but fails.
Meanwhile, Saitama sees a report about the Paradise Group and how every member is bald. To prevent people from associating him with the terrorists, Saitama decides to take care of the problem.
Speed-o'-Sound Sonic, a private mercenary shinobi hired by Zeniru, confronts the Paradisers and kills every member save Hammerhead. A brief scuffle ensues between the terrorist and the ninja. Sonic defeats Hammerhead, but the terrorist escapes.
Saitama, now in the woods in pursuit of the Paradisers, runs into Hammerhead. The terrorist attempts to kill Saitama but the hero punches back and destroys his armor. Saitama lets him leave and tells him to be good. Hammerhead flees. A short while later, two individuals of The Organization knock Hammerhead to the ground and mock his stupidity in stealing the suits.
Speed-o'-Sound Sonic arrives and asks Saitama where Hammerhead went. Sonic attacks Saitama twice, but Saitama stops blocks both attacks. He explains that he isn't a member of The Paradise Group but is instead a hero, but Sonic doesn't believe him. Sonic jumps around Saitama and shows off his speed, but Saitama follows his movements. Surprised, Sonic attacks Saitama but his momentum carries his crotch onto Saitama's fist. He jumps back and declares Saitama his eternal rival.
Back in his apartment, Genos tells Saitama about The National Super Hero Registry. The two decide to register.
- Speed-o'-Sound Sonic is introduced and after losing to Saitama, declares himself Saitama's rival.
- The Organization is introduced.
- After being defeated by Saitama and Sonic and nearly being killed by members of the Organization, Hammerhead decides to get a job.
- The Hero Association and heroes are introduced.
- To receive credit for their work, Genos and Saitama decide to join the Hero Association.