Ten Demon Apostles

The Ten Demon Apostles (テン悪魔の使徒, Ten Akuma no Shito) are an organization of powerful Demons, specifically Etherious, founded by Djed. They were brought to existance for the purposes of retrieving the ancient artifact ATOM. Their hideout is located in Balsam Village, where they disguise themselves as the Balsam Insurance Company.

History
The members of the Ten Demon Apostles are all Demons, specifically Etherious, making them Zeref's creations. Four hundred years ago, the Dragon Civil War took place in Fiore. Due to the critical circumstances they were forced under, a rebellious Etherious by the name Djed recruited nine other members who were also Etherious to rebel against the Dragon Civil War. As a result, they operated behind the shadows, until they were discovered by the Black Dragon Acnologia. Due to the encounter with the Black Dragon itself, many of the Etherious had succumbed to the Black Dragon's power and were no match for it, forcing the remaining members to flee for centuries. To ensure their survival, Djed himself sealed everyone into crucifixes and put them into lifespan-conserving tubes, bounding them to awaken after 399 years. After their eventual revival, Djed discovered an ancient artifact called ATOM, which was rumored to be able to infect the atoms and Eternano particles around the world, but at a great cost. So, they made it their purpose to retrieve the ancient artifact at all costs.

Purpose
400 Years Ago, the Ten Demon Apostles had an indifferent purpose. They sought obedience to Djed, and participated in the Dragon Civil War for the dominance of the Etherious, albeit operating in the shadows. However, after the mass murder of their brethren, they were sealed into crucifixes for 399 years. As a result, Djed gave himself and the Ten Apostles an ultimatum: retrieve the ancient artifact ATOM to revive their fallen brethren, or die trying.

Strength
Initially, they were stated to be one of the most powerful creations of Zeref, second only to the likes of his brother, E.N.D. Djed, their founder and leader, was stated to be able to defeat Mard Geer the Underworld King, had he fought for the sake of the Ten Demon Apostles and not have his powers chipped away as a sealing result. Every member of the Ten Demon Apostles prefer to utilize Curses more frequently than Magic, as this was to draw them back to achieving their ultimatum.

Furthermore, their power and dominance are classified through the numbers that are encrypted into them, ranking from 1 to 9. Once a member is killed, they will simply be "replaced" either by the one who killed the aforementioned member or recruited by Djed himself. There is also one more hidden member of the Ten Demon Apostles, dubbed as Number Zero. The mystery member is stated to be the Ten Demon Apostles' ultimate weapon.

Members
Note: To add a member, the user's character MUST be an Etherious.

Headquarters
Perhaps one of the strangest facts about the Ten Demon Apostles are their headquarters. It takes the form of a large company tower situated on Balsam Village, dubbed as the Balsam Insurance Company (バルサム保険会社, Barusamu Hoken Kaisha). Here, each member disguises themselves as humans and work as employees in the company, providing insurance to the citizens of Balsam Village.

Trivia

 * The organization if based off the Espada from Bleach.
 * The idea of their sealing period and method is based off Yhwach from Bleach.
 * The ancient artifact's name is based off the ingredient ATOM from Toriko.