The Seekers of Truth are a group of individuals led by Promestein who are trying to search for the truth of existence, knowing that the history of the world's creation is nothing but a fabricated lie made by Goddess Ilias. Ironically, they are not loyal to Ilias, but they serve her as a means of achieving their goal. Introduced in Chapter 3, they follow Ilias (or rather Promestein) in leading assaults or monitoring and experimenting on captured humans.
Their members are:
- Promestein: An angel and the leader of the Seekers of Truth, armed with vast technology and is the creator of the chimeras. Since the beginning she had a insatiable curiosity of the truth of existence which led her to being ridiculed by other angels who believed everything was a result of "Ilias's will," and was later imprisoned for "giving humans fire" and sparking their thirst for knowledge after acknowledging they could not survive by relying on Ilias and thus violating a rule that prohibits angels for coming into direct contact with humans before until Black Alice bargained for her release. Despite following Ilias's instruction of assaulting the the world, Promestein plots behind the scenes with her organization and Black Alice to not only overthrow Ilias but to also continue reaching her goal.
- Lily: A human who experimented on other humans in the Witch Hunt Village. While she is never seen with the other members of the organization, Lily claims to be "aiming to understand the truth of all creation" and refers to herself as "the Seeker of Truth." Following her defeat by Luka, it is implied Lily was replaced by Lucia.
- Lucia: A human alchemist who was experimented on by Lily and desires revenge on her and lost faith in humanity after the fact. It is presumed that she was recruited to Promestein's cause after Lily's defeat by Luka and was to replace her, with the goal of mastering the secrets of alchemy and learn the truth of the world.
- La Croix: A monster necromancer formerly known as Shirome Artiste and cut all connections with her little sister Chrome after an accident that turned Shirome into an undead. Extremely skilled in necromancy with her masterpiece Cirque du Croix containing many powerful queen-class monsters, she continues her goal of mastering all the dark arts and arrive at the truth.
- Laplace: A chimera who monitors the Drain Lab and exists to silently execute Promestein's commands. Despite being a machine, she was designed with a human "logical" thought process, which causes her to question her own existence after feeling many "illogical" things.
Although each member are from different races and have different motives, they all share the same goal of arriving at the truth of existence. To reach their goal, they overcome any obstacles, recruit fellow truth-seekers to their cause, and eliminate anyone, even a deity, who stands in their way.
In the end, all of the Seekers of Truth were defeated by Luka with majority of the members deceased: Promestein disintegrated from an experimental drug before declaring humanity as her rightful successor, Lily was imprisoned for her crimes, Lucia's faith in humanity was restored and works peacefully in seeking the truth without resorting to the organization's cruelty, La Croix was put to rest by Chrome, and Laplace self-destructed to prevent the Drain Lab from being compromised under Promestein's orders after finally arriving at her own truth of existence.