Most don't. I believe almost everyone involved had their memory erased or altered from what they said. Everyone except her dad and anyone from the 12 and Irumas grandad, because under demon law the 12 crowns can't have their memories meddled with.
I think they said from doing simple tests on Ameri, she basically inherited everything from her dad except maybe some visual traits. Genetically she is basically demon.
I also don't think the demons are necessarily disgusted by humans. Those that know humans are real either looks down on humans, or hate them because of the danger they pose to demons (temptation, power and giving in to their urges) from what I understand.
They erased the memories of everyone that was involved, just not the crowns
I also think that the way Sullivan watched Ameri's dad find love and fulfillment made him want to have someone too, that's why he used the portal to the human world to take Iruma. Or it's probably because they were looking for Delkira in the human world and Iruma just have the same energy as Delkira so he took him but ended up really loving him as a grandson. But I don't think he just took Iruma because of Delkira because I still believe he loves him as he is.
The question is, does Iruma have the same energy, or was it because of the ring that messed up his results? I do think something is up though, since Iruma got the ring. Yet parts of him are still definitely human
Long explanation ahead:
Demons DON'T hate humans, they see them as FOOD. Humans are extremely rare and considered the finest "FEAST." To demons, humans are an exquisite resource capable of granting overwhelming power if consumed, but they can also cause demons to lose control completely, becoming far more brutal and destructive than their original nature. This is why humans are described as a "potent drug." Because of this, humans are treated as a dangerous, almost legendary resource, and their existence is tightly controlled to maintain balance, often by claiming that "they don't exist," as stated by Marbas Marta, the former Vice-Chief of the Demon Border Patrol (Chapter 428)
In Ameri's case, the situation is much more complicated. Even though her origin involves a human (her mother, Merize), official examinations revealed that Azazel Ameri is biologically a full demon. Her mana capacity, reaction to blood, and physical characteristics all confirm demon classification, with her demon traits being stronger than any human influence (Chapter 441, Page 7).
Not many demons actually know the truth. Only a small number involved in the Border Patrol and confidential operations were informed. According to Marbas, Merize's existence traces back to a special assignment given to Henri, whose mission was to study and monitor humans (Chapter 429).
The only time information was shared outside the project was when Henri requested Sullivan's cooperation in creating translation magic so he could communicate directly with the human, Merize. However, Sullivan was likely never informed of the project's full purpose. He still agreed to help partly because Henri was his former student, partly because removing the language barrier would allow Henri to gather far more information, and partly because Sullivan jokingly mentioned it could be useful for future blackmail material.
A few demons from Babyls also became indirectly involved, including one of the 13 Crowns, Caim Caiman. Due to the Caim family's unique ability to understand, translate, and command the languages of other creatures, his assistance was valuable to the project. However, neither Caim nor the others appear to have been fully informed about Henri's true assignment. Most only knew fragments of what was happening and either lacked enough information to understand the full picture or never openly discussed it afterward. Some likely helped simply because Sullivan supported the request and found it interesting.
After the Vice-Chief learned that Sullivan had agreed to cooperate, he granted Henri permission to enter the observation pod, explaining that being able to communicate without language barriers would allow him to obtain significantly more information from the human. Even so, the project remained highly classified, with knowledge of its true purpose restricted to only a handful of individuals (Chapters 430–431).
It wasn't until Merize became pregnant that the 13 Crowns, the Three Greats, and the Substitute Demon King Kushinashi became involved. During labor, only select personnel described as the best medical specialists available and personally chosen by Kushinashi were present. Merize's health worsened, forcing Henri into an impossible decision: either keep her in the Demon World or let her return to the Human World. Realizing she would eventually die if she stayed and having no other solution, Henri chose to let her go, even though he could not accompany her (Chapters 437–442).
There was also extreme secrecy and memory manipulation involved. Before Merize returned to the Human World, the Substitute Demon King performed memory-altering magic. Kushinashi also confirmed that the door connecting the two worlds can only be used by humans, and that Ameri cannot pass through it. Furthermore, Ameri's examinations showed that her mana capacity, physical characteristics, and reactions all classify her biologically as a demon (Chapter 441, Page 7).
Henri's wish was to erase the memories of both Merize and Ameri. Everyone involved in Merize's labor was dealt with, and memories of Merize being human and Ameri being the child of a human and a demon were overwritten to prevent confusion.
Normally, it is forbidden to use memory-altering magic on the 13 Crowns. However, an exception was made in this case. Kushinashi personally met with each member individually, and a spell was placed to prevent the information from being revealed. In at least one instance, a separate deal was also made.
As a result, only a very small group knows the full truth about Ameri, including Kushinashi, the 13 Crowns, the Three Greats, Marbas, and a few others directly involved in the incident (Chapter 443).
So in conclusion, Ameri is not treated as a half-human by demon society. She is officially and biologically classified as a demon, and the truth of her birth is buried beneath strict secrecy, memory manipulation, and protection from some of the highest authorities in the Netherworld. That's why demons aren't attacking Ameri despite her mother's origins most don't know the truth, and even among those who do, Ameri is recognized as a demon, not a human.
Oh, I see. Thanks for the explanation everyone! I think I skipped some details (can't really focus reading long narrations/dialogues), I can't remember reading the part where they erased memories
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So, basically many demons know that Ameri is half-human, right??????????? cuz they knew her mother.......... so why are demons that are disgusted by humans not attacking Ameri???? She's also technically half-human, has human blood ...?