Saitama Group

The Saitama Group is a group of heroes that have affiliated with or hang out with Saitama. The group comprises of S-Class heroes, Saitama, and a few other heroes that often hang out with Saitama.

Overview
Although not an official organization, these group of heroes are 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. Saitama calls these people his acquaintances, but they've seemed to grown on him. As said by Fubuki, the strong seem to be attracted to Saitama, so she sometimes 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.

History
Fubuki challenged Saitama and his group to a competition where the losing team must obey the winner. The heroes who responded to Saitama's call were Genos, King, and Bang, much to the bewilderment of the Blizzard Group. The term "Saitama Group" was coined by Fubuki herself. Originally, the group consisted of these four members, but Fubuki has recently been affiliating herself with Saitama due to his attraction of strong members. In the webcomic, Overgrown Rover and Black Sperm followed Saitama home and are now affiliated with him. Although, they are more seen as pets and Saitama doesn't want much to do with them.

House of Evolution Arc
Before joining the Hero Association, Genos traveled from town to town to defeat monsters and evil organizations in order to try and find 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 disciple. Genos will later appear at Saitama's house a week later and thus begin the partnership between the two.

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 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 gamers. Since Saitama's group won the competition, the Blizzard Group would have to obey them.

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 the multitudes of S class heroes, all of which are incredibly strong in some shape or form (bar King).
 * The group was founded naturally, without any initiation or recommendations to establish such group and acts much more akin to normal human side of the otherwise extraordinary individuals.
 * So far Saitama Group is the only group that owns a group under its command, notably Blizzard Group that lost through video game bet.