Adventurers Association.
They were the largest association that existed on the Averus Continent.
The Adventurer's Association was spread throughout the human kingdoms.
In every human kingdom, there must be an Adventurer's Association. However, the Adventurer's Association in one kingdom was different from the Adventurer's Association in another kingdom.
Each Adventurer's Association in another kingdom had a different leader.
Not only the leader, but the system implemented in the association must also be different, in terms of administration, regulatory policies, laws, and others.
In short, different kingdoms had different Associations. Although they all seem different, they share the name 'Adventurers Association'.
If this was Earth, a trademark battle over the use of the name 'Adventurer Association' would already be happened. It was a good thing that there weren't any such laws in this world.