The history of the Hero Association has its roots with the first hero, Shiningman and the project known as the S Project. It was actually a small experiment, with the intent to bring a ray of hope to an otherwise miserable and violent society. Initially, it was successful as Japan's citizens soon became enamored with 'hero fever.' This in turn caused many businesses to consider using heroes as corporate spokespeople for their products and services. Sometime before the start of the series, Shiningman disappears, and the people who were involved with the S Project were either dead or went into hiding. Only Shouichirou Kizaki was left, along with whatever technology and resources that remained of the project. Using those remnants, low level superpowers were made available to the public. So to regulate those abilities, the Hero Association was created to issue licenses, enforce rules of conduct, as well as help the public interact with the heroes.
However, the true goal of the Association may not be as benevolent toward the citizens as one might think. Due to the expense of maintaining superpowers, most Heroes are commercialized and promote the products and services of the companies they represent. Though there are many Heroes who truly wish to help the people, there are just as many who are registered for purely selfish motives. Since the crime rate has admittedly dropped due to the number of heroes, there is stiff competition among them in order to achieve higher rankings, which can lead to public endangerment and infighting between the Association members, (like the D-Rank Duo and the Gem Unit of PRISMMAN). Additionally, the Association is not above corruption within itself, (such as Dr. Teramishi and Takaki).
Furthermore, there seems to be a hidden agenda with its president. He employs the S-Rank heroes as a kind of secret police force; controls nearly all of the media to keep bad press away from the Association, and has some secret project with connections to Shiningman, Crea and Mirea's parents, and ultimately Ratman. This current experiment undoubtedly has its roots in the original S Project and its legacy, and the Association's rival Jackal.
First Crime Arc
The Hero Association gets its first direct attack against it as a mysterious figure known as Ratman breaks into the President's home and steals all the files concerning the identities of its heroes, and later posting that information on the Internet. The leak is put down the very next day as the Association considers this as a declaration of war. Ratman is now on the Wanted List.
Hero Awards Arc
Due to a fight among the members of the Gem Unit of PRISIMAN, a fire breaks out at a hotel, thereby putting many innocent civilians in danger. Though Ratman appears on the scene and is initally blamed for the fire, the Hero Association suffers its first major hit as two A Rank heroes are unable to take down the supposed villain, with Ankaiser being seriously injured. The threat level that Ratman represents is now considered grave enough for the S Rank Heroes to get involved.
Threat of S Arc
After a few more sightings of Ratman, S Rank Hero Kreios confronts the so-called villain and tests out his abilities. Though Ratman possesses formidable powers, he is unable to control them and is suspected of having the S Gene. The order to capture him is suspended until further investigation.
After Ankaiser recovers from his injuries and gets an upgrade to his hero powers, he and Van Guardner are sent to shut down a major drug ring. All the damage and the fact that G9 was working for the drug lord was covered up and blamed on the criminals. Meanwhile, unknown to the Hero Association, Dr. Teramishi and Takaki have been secretly diverting funds and resources to the Bio-Experiment Lab in order to further enhance their own S Rank Hero Unchain. However, when Rio goes missing and the heroes are sent out to search for her, the Hero Killers are unleashed on the public. Despite the Hero Association's best efforts, it is ironically Jackal and Ratman who stop the source of the chaos.The conspirators are arrested and like all the other incidents, this one is covered up from the public.
After learning of Ratman having the S Gene, Rio's father had hoped to keep him a secret from the public. However, due to Ankaiser issuing a challenge to Ratman for a rematch during a press conference, the issue becomes irrelevant. Rumors about Ratman begin to spread, which in turn begins to have people question the Association.
Hero Booster Arc
The Hero Association gets its worst PR nightmare as low-ranking heroes suddenly have their powers enhanced and go on a rampage. Kreios begins to suspect Crea is behind the chaos as part of her revenge against the Association, but the real instigator is IS-KA. With the heroes now fighting amongst themselves and the public being threatened, Rio's father begins to think that this is one incident which cannot be covered up completely.
However, like the Hero Killers, Crea and her grandfather are able to shut down the source of the madness, leaving the Association once again in debt to Jackal.
Hero Booster Aftermath
After covering up what they could of the incident, Rio's father decides to finally confront the leader of the rival organization. After what could be called as 'dodging the bullet' concerning his talk with Crea, the two organizations seem to be on a tentative truce.
The Hero Association has complete control over all heroes. No one can be called a "hero" without obtaining an official license from the Association.
The process to becoming a hero has not yet been fully explained, though there are indications of passing an initial exam and registration. Since most heroes are commercially sponsored, it is reasonable to assume that it is the companies who register with the Association, and therefore also register their representative heroes.
Heroes are ranked in terms of the corporations they represent and their power levels. So far there are seven categories. Those who belong to the lower levels can raise their ranking stats with more acts of heroism, or if they have enough money to buy better abilities, thereby receiving better contracts. There's also a physical upgrade test in which a hero can raise his/her ranks by raising his/her power levels. Conversely, there are situations in which a hero can be demoted in rank, (such as committing an act that makes the hero, and the Association look bad, or if the company that represents the hero goes under, thereby being unable to keep up with the payments).
Apparently there are some rules and regulations when joining with the Hero Association. Ankaiser had to give up his boxing license when he joined up. In doing so, he could never regain his right to box professionally, if he were to leave the Association, (most likely due to the fact of being physically enhanced as a hero). In addition, the higher the Hero Ranking, the more benefits a hero and his/her family receives.
S-Rank:The highest category. These 'heroes' are mostly unknown to the public and serves as the Hero Association's secret police. They have the strongest powers and may also be linked to the S Gene. Characters such as Kreios and Unchain are in this category. By definition, Ratman may also qualify, (though he is unlicensed and inexperienced), since he has the S Gene and has defeated an S-Type hero, (Unchain). Most likely their benefits are at the highest levels, though these heroes stay out of the public limelight for the most part.
A-Rank : Well known by the public and are considered the most powerful, (though not as strong as the S-Rank heroes). They usually represent large corporations such as security firms. Ankaiser, Van Guardner, Heavenly Maiden and others are in this category, (though currently, Ankaiser is now a D-Rank). They are the figureheads of the Hero Association, and their public images must be maintained at all times, even when they commit acts that would be considered as criminal or endangers innocents such as Ankaiser causing the large explosion when fighting G9 was blamed on the criminals. Benefits are quite high and a hero's family is given the best medical care.
C-Rank :These heroes are around the middle-level of power levels, and they interact more with the general public than the higher-ranked heroes. They also represent the smaller shops. The Akiba Holy Girls belong to this category.
D-Rank : Possibly the lowest ranking-heroes that assist in fighting crime and have been known to work with police to catch small-time criminals such as robbers, muggers and those who disturb the peace. These represent the minor companies. They are also equipped with low-level abilities that aren't always effective. Strength-wise, they are considered as average, with a few exceptions. The D-Rank Duo and Mr. Carsonbo would qualify in this category. Ankaiser is now part of this ranking as he is the superhero for the Kaiser Boxing Gym, though he intends to raise himself back to A-Rank within 6 months.
E-Rank: These members are more like company mascots rather than heroes and have presumably the lowest level of powers. As such, they are not expected to fight crime. Fatman and Mr. Big Horn fit this category, though they were later upgraded to D and C-Rank respectively in Volume 9.
F-Rank: Introduced after the Hero Killers incident, at around Chapter 35. These members have no powers to speak of and are more or less used as spokespeople for small groups or bands. Like the E-Ranks, they are not supposed to endanger themselves or the public by trying to act as crime-fighters. Yavais is the first hero to be recognized in this ranking.