D-Rank Heroes are considered for the most part to be the weakest of all the heroes who assist in stopping crime and keeping the peace. Their strength levels are considered average and this is the level in which most new heroes start at, unless they are below average or not intended for crimefighting, (such as the E and F Ranks). These heroes are considered minor and some do commit reckless acts in order to raise their rankings. Others simply try to promote their company's services and products.
It has been shown that many D-Ranks are unhappy with their low levels and will do anything to raise it. Since there are many other heroes of varying ranks, there is fierce competition among the rescuers and crimefighters, (especially since the crime rate has dropped due to the presence of heroes).
One example of how desperate the D-Ranks are to raise their status is the D-Rank Duo, who discharge their weapons in public, thereby endangering innocent bystanders. Fatman is eventually raised to D-Rank, due to his business becoming more successful and his own heroics.There are exceptions to this category of heroes such as Ankaiser and IS-KA . Ankaiser had to start over as a D-Rank after ANK Securities went bankrupt and he re-registered with Kaiser Gym. IS-KA also started as a D-Rank, but is actually able to go toe-to-to with A-Rank hero Heavenly Maiden and was rapidly promoted to B-Rank in just under 3 weeks. This in turn caused a lot of animosity among the lower ranks and especially the D-Ranks as they saw it as taking away their means for advancement. They became so desparate to raise their own levels that they began looking for illegal methods to promote themselves, leading to the Hero Booster incident, in which many went berserk on the streets.
This is a list of D Rank Heroes from the Hero Association.