Saitama Group

The Saitama Group, called the "New Blizzard Group" by Fubuki, is a group of individuals that have affiliated themselves with or hang out with Saitama.

Overview
Although not an official organization, this group of heroes includes those who have affiliated themselves with Saitama or usually hang out with him. These heroes were originally the ones who responded to Saitama's call about Fubuki's challenge. Saitama calls these people his acquaintances, but they've seemed to have grown on him. As said by Fubuki, the strong seem to be attracted to Saitama, so she tentatively affiliates herself with him as well. They are usually invited to Saitama's apartment cookouts or to play video games (usually just King). Saitama and Genos have periodically been invited to Bang's dojo and King has often invited Saitama to come to his apartment to play video games or vice versa. However, Fubuki sees Saitama's group as another branch of the Blizzard Group.

Despite the small membership, the group is immensely powerful and has the capability of taking on extremely powerful Dragon-level threats, even with Saitama out of the scenario. Certain individuals within the group are able to take on Demon-level threats alone and come out victorious, showing greater prowess than the capabilities of even groups of heroes.

House of Evolution Arc
Before joining the Hero Association, Genos traveled from town to town to defeat monsters and evil organizations in order to find clues on the evil cyborg that killed his family. At Z-City, Genos is facing off against the House of Evolution's Mosquito Girl and eventually starts getting beaten down. Genos is about to self-destruct until Saitama interferes and slaps Mosquito Girl, killing her. Genos, greatly surprised by this, asks Saitama his name and wishes to be his disciple. Genos will later appear at Saitama's house a week later and thus begin the partnership between the two.

Monster Association Arc
Bang and Bomb come to Genos' aid as he is fighting Garou. The two martial artists continue to beat down Garou as Genos watches in awe. Garou eventually powers up in a fit of fury and rage, but they are interrupted by monsters from the Monster Association. They manage to kill off the monsters, but Phoenix Man saves Garou and calls in Elder Centipede. Despite the efforts of the two powerful martial artists and Genos, they are unable to defeat Elder Centipede. They are forced to run away in order to save the heroes but face a dilemma of whether to try and fight the centipede once again or lead it into S-City at the cost of many lives. Eventually, King arrives at the scene, announcing to Elder Centipede that Blast is with him so that the monster can exact revenge on the rank 1 S-Class hero. As the monster charges at King, Saitama comes out behind King and kills the monster with a serious punch.

The Saitama Group regroups at Saitama's apartment after the fight with Garou, Elder Centipede, and some of the monsters from the Monster Association. Fubuki visits and sees that King and Saitama are playing video games, Bang and Bomb are recovering, and Genos is repairing himself. She informs them about the growing threat of the Monster Association and needs for them to act, but Genos states that they just fought a battle. It is revealed here that Genos, Bang, and King's communicators with the Hero Association have been destroyed due to their fight with the monsters. While Bang, King, Bomb, and Genos stay back to recover (although King says he just has other things to do) Saitama heads out to hunt for Garou and buy some cabbage. Fubuki thinks to herself that getting Saitama to join her group will be harder than she thought.

Saitama finished his meal but discovers that he lost his wallet. Fubuki finds him and offers a guaranteed top 5 B-Class rank as long as he obeys Fubuki and getting 70% of the credit. Instead, Saitama leaves to chase after a dine-and-dasher, leaving Fubuki with the bill by tricking her into eating an extra order of french fries. Saitama eventually returns to his apartment whereupon King, Bang, Bomb and Genos are worried over Saitama's state of mood. Fubuki returns with the cabbage that Saitama left behind and is angry at Saitama for ditching her. Soon afterwards, Dr. Kuseno visits in full battle gear expecting Genos to be in danger because of his distress signal. After finding Genos fine, he gifts Saitama with expensive beef. Saitama's group share a hotpot together with the expensive beef, tofu, cabbage and various other food.

In the webcomic, Overgrown Rover and Black Sperm followed Saitama home and are now affiliated with him. Although, they are more seen as pests and Saitama doesn't want much to do with them.

Numbers
After being challenged by Fubuki, Saitama arrived with his group which consisted of S-Class heroes Genos, King, and Bang. However, this was all according to a plan by Fubuki, and she made them sign a contract without them even reading it. Instead of a head-on physical battle, Fubuki insisted on a video game competition. Bang, Genos, and Saitama are quickly taken out of the competition. King was able to single-handedly take out her thirty members. Since Saitama's group won the competition, the Blizzard Group would have to obey them. In the end Fubuki took them out to a restaurant where she ordered steak.

Trivia

 * The heroes within the group acknowledge Saitama's true strength and are the few individuals who truly see him for who he is despite his outward appearance.
 * The group itself is technically the strongest group within the series as it contains Saitama himself along with other high-ranking heroes, all of which are incredibly strong in some shape or form.
 * So far the Saitama Group is the only group that owns a group under its command, notably the Blizzard Group that lost through the video game bet, although how much control the Saitama Group has over the Blizzard Group is not clear as Bang wanted disciples which he does not have from the Blizzard group.