Essential Demon Lore Mechanic Translations


Transalation and Article written by KotodamaTL

These translations are mainly as preparation for my translation of Decoration Disorder Disconnection (DDD) so that it all makes sense.

It covers the mechanics of the demon lore, so sadly no lengthy Merem Solomon translations here or other showcases of this lore, mainly because of time-budgeting.


Spoilers below for: Tsukihime, Fate/Stay Night, Hollow Ataraxia, DDD, and Fate/Extra CCC.

From the Translator

Okay so, a lot of preamble to cover. Don't worry, there's a summary of the lore I cover here below but there's a lot to cover because demon lore as it is currently is an unnecessary mess. Feel free to skim this and scroll to the next header if it's too much.

I don't want to turn this into a Japanese lesson, but I want to be clear that I can't fix everything so I'm going to have to train you on what to actually look out for to "autocorrect" past and future mistranslations from the likes of Fate/Grand Order North America ("Daemon" and "Demon" is stupid for reasons I'll cover), Melty Blood: Type Lumina's embarrassing official translation (Kaibutsu/Monster as Demon wtf but Kouma is part Oni which isn't a Demon in Nasuverse lore exactly), but also a lot of intelligent and well-meaning fan translations.

Demon lore is often translated poorly for several reasons (Demons not being that popular for one, neither is DDD where it's relevant, Extra CCC was in Pending Translation hell for years for the sake of integrating it into the game), but it is primarily the confusion with how Nasu changes synonyms to mean different things like how Majutsu and Mahou are Magecraft and Magic, Ma are "Aberrations", for the lack of an "official" English word to express "Demon but not quite", I had to pull this term from Dungeons & Dragons (Nasu borrows concepts from D&D anyway so I think it works), and Akuma -- "Demons" are just Demons, none of this "Daemon" nonsense which muddies the lore of the wider Nasuverse as a whole because if the Greek Guardian Spirits "Daemons" ever show up or come up in any form of lore discussion, that "translation" falls apart completely... even if the word roots are essentially the same. It's just bad, okay? You'll have to do the research or trust me on this one.

I've had a whole dictionary's worth of potential translations to translate the demon lore and I'm certain someone is going to disagree with my reasoning, all I can say to that without sounding like I'm tooting my own horn is that I'm the one who's actually bothering to translate these terms with the intent of translating DDD (where this lore actually comes up in a story in a meaningful way), and that might sound rude but it's just being assertive, I just hope this style guide reads well for our purposes. Rest assured, I have the reader's best intentions in mind and I think about this a lot.

A much needed summary...

Okay so to recap, Aberrations are the wider classification and Demons are special and not everything gets to be a Demon, while all Demons are Aberrations but not all Aberrations are Demons.

Oni are different and so they shouldn't be translated as Demons but I'm not covering them here because they should really have their own translation deep dive. Some of the lore here is tangentially related. You'll see what I mean.

Colorful MOON Tsukihime (2002-09-01)


A color of the realm of the gods. The ideations and Pure Eyes of those whose existence approaches the realm of the gods are of this color.


A color symbolic of aberrations, such as demons. The ideations and eyes of those involved with aberrations have long had the tendency to be this color.


A color symbolic of aberrations, such as demons. Arcueid’s eyes can change to this color.


A color of the realm of the gods. It's said that it can be seen in the ideations of those whose existence approaches the realm of the gods


①Aberrations are a part of the law of nature itself, but their existence is unnecessary to nature since their powers distort the flows of natural power.

②Their mere existence is a distortion. Therefore, demon hunters seek to exterminate them as soon as possible.

Demon Hunter

At least from a Japanese perspective, this can refer to:
① A person (or a group of people) that work to correct distortions of nature, aberrations.

② A family or bloodline or magi that refines their techniques in order to protect society.

③ A Demon Hunter Organization.

④ As far as ① and ② are concerned, the people in these categories generally don’t have powers that are suited to bringing harm to somebody else. They are at a disadvantage against someone with mixed-blood, who is on the borderline of being human.

Demon Hunter Organization

At least from a Japanese perspective, this can refer to:

① An organization that exterminates aberrations, such as demons.

② An organization created in order to protect society.

③ Therefore, these people generally don’t have powers that are suited to bringing harm to somebody else. They are at a disadvantage against someone with mixed-blood, who is on the borderline of being human.


① First, let’s begin with clearing up the literal meaning of “marble.” It can mean “marble” as in the type of stone like “a marble floor” or “a marble pillar.” It can also mean “marble” as in a small glass ball. Let’s set this aside for now.

② Next, let’s clear up the meaning of “clustering illusion.” When you search for this term along with the word “probability” you can find an example about a jar which is filled with marbles of two colors, white and black. After you fill the jar and mix up the marbles inside, instead of the marbles appearing like a chess board, with the colors equally and evenly mixed together in a checker pattern, you will notice clumps of white marbles and clumps of black marbles here and there in the jar. These clumps, which seem non-random, despite actually being randomly distributed, are the clustering illusion.

③ From the above explanation you can see that the term marble comes from marble in the glass ball sense, not the marble floor sense of the word.

④ Even in a situation where you have half black marbles and half white ones and you mix them up, “logically” you assume that the white and black should be evenly mixed since there are equal amounts, but when you check the result you don’t see an even mix, you see clumps and groups in the pattern. This is precisely where clustering illusion comes in, and the result of a series of random coincidences may seem as though it was purposefully realized by someone, despite it actually being a natural phenomenon. So when probability itself is being interfered with, one might understand that materializing Brunstud Castle might not be so implausible . Therefore, when the world is connected with a marble phantasm or reality marble, probability is interfered with, and a series of phenomena, which could only ever be considered to be random coincidences, is deliberately generated.

Marble Phantasm

① Imagination Materialization. (See the entry for “Marble”)

② The name “marble” comes from glass marbles used in a well-known example of the clustering illusion.

③ The user directly connects and imposes their will on the world which creates an interference that transforms the world as they see fit (as they imagine). They make reality an illusion (something impossible in reality).

④ To be specific, it is thought that because it is the interference of the "probability" of a great number of phenomena occurring, by nature, a Marble Phantasm can forcibly cause impossible phenomena to occur.

⑤ It is thought because a Marble Phantasm has interfered with the probability of phenomena occurring, the ability isn't limited to materializing physical objects.

⑥ In the world of Tsukihime, Marble Phantasms are the manifestations of parts of strange realms that exist on top of the normal world, these fantasy worlds are born from the imagination of Natural Spirits. Therefore, it's possible for regular humans to wander into a Marble Phantasm.


Because it is possible for the practicioner to transform the world as they wish, it is extremely versatile.


It can only transform nature, and it cannot directly interfere with entities independent of nature (such as humans). Therefore, it must materialize something else to indirectly interfere with such entities.

Reality Marble

① Intrinsic Bounded Field (Also see the entry for “Marble”)

② The name “marble” comes from glass marbles used in a well-known example of the clustering illusion.

③ A subspecies of Marble Phantasm. It is a form of world interference that erodes reality as the practitioner materializes their mental world.

④ To be specific, it is thought that because it is the interference of the "probability" of a great number of phenomena occurring, by nature, a Reality Marble can forcibly cause impossible phenomena to occur.

⑤ Originally, it was was associated with the foreign common sense of Demons. But despite it being the ability of Natural Spirits and Demons, it is possible to perfect the Magecraft necessary to manifest one's own mental world after many long years. There are a few top magi, Dead Apostle Ancestors, and others who are capable of using a Reality Marble.

⑥ However, a Reality Marble is a foreign world, so unless the creator is an extension of nature like a Natural Spirit, the Reality Marble and any creations from it are subject to being corrected by the real world.


Unlike a Marble Phantasm, a Reality Marble can interfere with entities independent of nature (such as humans).


A Reality Marble is, strictly speaking, the practitioner's inner self given form, so its form is unable to be consciously decided by the user. Therefore, its versatility is low.

Fate/Stay Night (2004-01-30)


Just as The Sixth Imaginary Element known as Demons require "the form created by humans" to manifest themselves, the Heroic Spirits also need a form to live in this world.

DDD Chapter 1 - Junk the Eater (2004-07)

(was released in Faust magazine)

Fate/Hollow Ataraxia (2005-10-28)

Heaven's Feel Backnight I

The remaining magical energy traces were extremely dense.

Magical energy is only fuel for activating magecraft. It does not show any effects by itself.

However, there are exceptions to this rule. It can leave behind a form, but only when that magical energy itself possesses special characteristics close to magecraft.

For exampleーーーI have heard that the Einzberns gave a personality to their Holy Grail.

If that personality has magical energy, then it naturally possesses the magical trait of "wish granting."

Since its vital activity and its functions as a Holy Grail are likely directly connected to each other, it should be able to perform miracles resembling "magecraft" simply by releasing magical energy.

The "incarnated aberrations" spoken of by the Holy Church also fit this example.

Beings created as "aberrations", before they were lifeforms, can use more advanced magecraft than humans.

As magi, our magic circuits are nothing more than pseudo-nerves.
An ability that was added later behind our nervous systems.

However————"aberrations" have no need for psuedo-nerves.
All of their organic functions serve the purpose of invoking "aberrant" phenomena.

I hear the Church call these "True Demons."
Differing from the imposters that clad themselves with human thoughts to gain "distinct names", they are genuine "demons" that the Lord commanded before man would name them, or so I hear.

Heaven's Feel Backnight II

Bazett: "I have a more pressing question. You said that we would be revived as long as we were killed during the evening. Is there some sort of cost to this? For example, losing my magic circuits? Or is there a limit to the number of times you may use your Noble Phantasm?"

Avenger: ""Hm? Nah, there's no cost. You don't have to give up a dime. My attribute is Emptiness. As long as there is Nothingness, we'll be resurrected any number of times. Just relax and keep going until you're satisfied."

(Story Note: Avenger / "Angra Mainyu" is a Demon because of the wishes of the people from their village via the grail. When Hollow Ataraxia later references the demonic grail, Akuma / Demon is furigana about Seihai / Grail so it is very over that the corrupted grail is a Demon by extension. I would say, in my personal interpretation, there's no evidence to indicate that servants blackened by the grail are demons because this would have been stated either immediately in Fate/Stay Night, or in other works like Fate/Grand Order)

Caren I

Caren: "You are mistaken. Emiya Shirou. Have you ever heard of the term "demonic possession"?"

Shirou (Avenger): "Demonic possession...?"

I remember hearing about it.
It's one of the spiritual disorders that's well-known in the west. The Japanese equivalent would be something like being possessed by a Kitsune or Inugami.
An inhuman "something" that possesses humans and starts breaking them down from the inside, similar to a curse.

The symptoms are too broad to be systematized, but these western possessions are usually caused by an outbreak of the very concept of "demons."
For reasons, or criteria that human intelligence cannot grasp, demons tend to possess good-natured humans. Compared to the Japanese concept of possession which is based on the will of "those behind the curse", Western "curses" are phenomena occurring with no intention at all, like traffic accidents.

Those who are possessed are usually ordinary, good-natured people.
Their minds are afflicted with mental illnesses, disparaging morality and God's teachings, and they go on to terrorize those around them. Not by direct violence, but by showing them the repulsive creatures humans become just by being stripped of reason.

However, these are just the early symptoms of demonic possession.
The degradation of those have been possessed for a long time isn't limited to the mental level alone.

Severe "possessions" even change the victim on the physical level.
... The formless "thing" will attempt to incarnate within the host's body.
The transformation starts with the development of an unimaginable level of body control for a normal human being, and goes on until the body parts are mutated.
The mutations depend on the rank of the "thing." The stronger the demon is, the further away from human the victim transforms.

...But fortunately, an aberration cannot be incarnated within a human body.
A person who is possessed will be forced into an unnatural translation and simply die as a result. The western depicted demons all look rather weird.
Two heads, hooves, or limbs arranged into the shape of a hexagram. Definitely not something a human with only one set of arms and legs could imitate.


It's said that there are rare cases of humans being able to endure these transformations. Like how magi craving secret arts become vampires, heretics extend their lifespans by utilizing the 'things' that devour the blueprints known as their souls."

So, this woman is...

Caren: "...That too is a misunderstanding. While it is irrelevant to the matter at hand, I used to serve as an exorcist's assistant. I was never possessed, and I do not believe I ever will be. A demon requires a healthy body. It cannot take root in mine."

Avenger: “? Well if that’s the case, why did you start bringing up Demonic Possession in the first place? If you said your body was possessed by a demon, I’d understand to some extent but--”

Caren: "...Porca miseria."

Avenger: "Uh... did you just say something really mean?"

Caren: "I just said, "What an impatient person." ...We shall get to the real issue right after this. Just listen, please."

Caren: "Being possessed will produce many forms of supernatural symptoms. Like knocking sounds that are associated with a poltergeist disturbing its surroundings, or interference with the host's body. ...You could say it's a disease that only affects the host. It is a poison that does not spread to others like a virus would."

Avenger: "No kidding. If you could catch demon like a cold, I doubt there'd be any normal humans left by now."

Caren: "That’s probably true. However, just like how humans with high supernatural awareness have the ability to sense aberrations, there are also humans that experience the same spiritual symptoms of possession victims just by being near them.
Frankly speaking, I’m talking about myself. Whenever I get close to something that is possessed by a “demonic” presence, my body will reproduce the exact same spiritual symptoms that the demon would have caused.

My master called it Masochistic Spirit Medium Syndrome."

No pause or hesitation.
Caren has just said something that might send me straight into a major depression if I think about it too hard.

Avenger: "...What? So, basically, you will turn into a demon if you get near one?"

Caren: "...Although that is an idiotic response, let's just stay it's correct.
To be exact, it is an automatic reproduction of spiritual damage of aberrant origin."

Caren: "Let us say you got infected with a cold. Assume that it is still during the early stages before the symptoms show, so your body just feels a little heavy.
...Now if I get near you, the symptoms that will eventually be caused by that disease would appear in me. The number of patients increased to two, so to say."

Caren: "...While it seems that it caused you harm, this trait generally isn’t an issue for other people.
So please, don’t worry about it from now on."

Avenger: "...Even if you say so...
Well, I wasn't worried in the first place, but no surprise attacks, alright? I just can't shake this feeling that getting close to you will cause a lot of pain."

Caren: "I suppose that’s true. I am frequently under demonic influence. Yourself aside, Shirou Emiya, the presence of monsters will have an effect. If you find this prospect frightening, you shall do well by staying away from me whenever they are nearby."

I don't understand it, but this is one bit advice I should probably follow.
Alright unless things get serious, let's try to not get too close.
Randomly hurting each other is no good.

Avenger: “So back then...”

Caren: "...Most likely. It was probably the incarnation of the spiritual damage belonging to those monsters.
While they rank low, it seems that they have a connection to demons."

In other words, if they aren't near, she won't go nuts either?
...If so, would those monsters' symptoms be, "creation of the same monster"?

Caren: "We shall leave my traits aside for now. How about we continue with your questions?"

Caren II

However, she was not invited to be a Cistercian Nun.
An Agent.
She was delivered only as an armament of the Church for assistance in the exorcism of Demons.

A weapon is intended to be guided by the hands of men.
She was permitted to leave the monastery only when her unusual talents were required to make known the Lord’s might.

The might of the Lord was not meant to be turned towards the sons of man.
It should be aimed at those wild ones who fear not the Lord, the aberrations who threaten the Son of Man. Aberrations who possess people in order to give form to their evil.
"To cleanse this person and reveal the love of God to the sons of man", that was the task given to the woman, no, to the agent using the woman.

The woman was used for exorcising demons.
Special priests, allowed to act as "representatives" from the bishops of the diocese.
They answer calls for help, visiting the towns of the possessed to exorcise demons.

It was closer to fighting than praying.

Her master frequently said to himself that the work was like washing the bottom of Hell's cauldron.

Exorcisms vary in severity, and the cases that her master took on were particularly intense ordeals.
It doesn't concern impostors attempting to deceive us by blaming their own self-destruction on the acts of demons, nor does it concern monsters resembling epidemics.
Their opponents were only those who had completely "become" demons.

The tragedy caused by a True Demon isn't something that can be endured with a human mind. All of the towns visited by the exorcist had deviated from the human world. The damage caused by an aberration is not limited to the possessed, it also spreads to the people around them.

――Going beyond the possession victim's physical abnormalities, their spirits, rather than their bodies, are twisted into a more grotesque form.

As her master would say, it wasn't far from a tour of Hell itself.

In an exorcism, the most fatal vulnerability is none other than human reasoning.

The body's survivability is not that important.

Because a human's abilities cannot compete with someone who has 'turned' into a demon anyway.

The physical body is protected by a holy relic embodying the miracle of the Lord.
However, the spirit — the soul — must be defended with one's own will.
What is required in an exorcism is ironclad faith.
In that respect too, the woman was well suited for the exorcism of demons.
It was fortunate that she didn't have a wide range of emotions.
The exorcism of a True Demon is considered to be something that cannot be endured twice, and yet she continued to go through them indifferently.

The woman was very useful.
She had the life of a nun and the role as an agent of the Church.
The workload was nothing short of backbreaking.
It probably would have overcome any normal person within a month's time.

Caren: "I do not do anything. I have not been granted the rites, nor sacraments to exorcise a demon. I simply accompany my master."

Avenger: "Huh? You mean you just follow him around? That's it?"

What the hell?
Is this guy she's calling "master" a wimp?

Don't tell me he was just too scared to go to towns where the possessed were by himself.

Caren: "I won't ask what you're getting angry about, but that is an over-simplification. Those who become exorcists do not fear demons. What they do fear is the shattering of their own mind."

Avenger: "・・・・・・Huh. That's impressive and all but if that's the case, he'd be okay if he just exorcised them all by himself, right? Isn't it unnecessary for you to get involved? I mean, what about that "Masochistic Spirit Medium Disorder" thing you have? If you get close to a demon, you'd get the same symptoms as the possessed guy, right? And if that’s the case, you’d be a nuisance rather than an assistant. It’s like jumping into a fire while covered in gasoline."

Caren: "That is my role. To take spiritual damage.
Because that is the quickest way to identify an aberration.
Demons are invisible to the human eye, it doesn’t become apparent that someone is possessed until they transform. Or rather, True Demons are clever, so they conceal themselves within the possessed. So as to not attract the attention of enemies until reaching maturity, they try to suppress their spiritual damage as much as they can."

Caren: "...Unfortunately the church has no way to exorcise fully-matured demons. The only thing exorcists can do is find the possessed before they can mature and exorcise them.
Once they have become a demon, we have no choice but to incinerate them.
Only an agent specializing in heretic inquisition would be able to do that."

Demons can’t be seen by humans. Only the host knows they are possessed.
The first, and most difficult step in an exorcism is finding the demon that conceals its true identity.
Even for a skilled exorcist, identifying a demon is like walking on a tightrope at all times.

This is where she's useful.
She has an idiosyncrasy that responds lustfully to surrounding demons, evil spirits, and the like, and causes the effects of the possession on its own.
If you look at it from the Church's perspective, it's an extraordinary "heresy."
Although it would normally be a useless physical disorder that would cause her harm just by being alive, there is one specific purpose that shows off its ground-breaking effectiveness.

In short...

This girl is a living detector that sheds blood to inform others of demons.

It makes a tearing noise.
It breaks her arms, crushes her legs, and rips her womb from the inside.
Even if the form returns, the function does not.
The sight from those dull, golden eyes was lost long ago.
I doubt her bell-like voice could ever make a sound again.

… These are her true colors.

She is a messenger of God, who saves others by mutilating herself until her death.

Avenger: “...Just asking, but can you refuse?
You can’t right? Surely you'd have refused if you could.”

Caren: "That is also incorrect.
The Church is strict, but not inhumane. One has the right to refuse participation in an exorcism.”

Avenger: “----So why do you bother helping with the exorcisms?”

Caren: “Because there is meaning in it.
Besides, neither outside nor inside are any different to me.”

Going outside to perform exorcisms and being inside the monastery are no different.

...Ah, so that’s it.

I had thought before that she was riddled with bandages and reeked of disinfectant, but it’s no wonder.

An Aberration stings at the very heart of a human.

No matter where she goes, she can’t avoid getting hurt.

Avenger: "That’s total bullshit. That’s not a good reason to take part in exorcisms.
Don’t you even have one complaint?”

Caren: “I understand that I have a handicap compared to others, but that’s what I was born with.
There is no point feeling bitter about it. If I was born this way, I just have to abide by my fate.”

Avenger: “What? Haven’t you thought about curing it? If it’s something like a disease, at least do something to improve your health.”

Caren: “There is no hope for a cure, nor do I wish for one. It is enough just to be able to pity myself over my misfortune.

ーーーーBesides, although I certainly do become injured, those are not my wounds, but rather those of someone else. It is pity I have, rather than resentment.”

Caren IV

Caren: "Ugh...!"

There is a subtle sound like the tearing of vinyl.
The scent of blood spills out from the bottom of her vestments.

Avenger: "? What's wrong? Your period?"

Caren: "It is only a wound opening up, I apologise, but, um…"

Avenger: "Yeah, I'll move back a row. Sorry, that was completely my fault."

"There we go", I move to the seat behind me.

Now that I'm a little further away, the scent of blood is fainter.

"That must be tough on you. You're still wandering the streets at night even with those wounds opening up."

Caren: "...Hm, that's right. I recall you dutifully searching for me on the fourth day. Of course, that is not the only reason for my fatigue.

...Recently, I have started an imitation of a demon exorcism."

Avenger: "Ohh."

I wasn't actually paying attention.

To be honest, just because the smell of blood is fainter now doesn't mean I'm completely in control.

For instance, my eyes are fixated on the wounds hidden by those white bandages.

And by those slender arms and shoulders that seem as if they'd break just by being held down.

Or even by her white belly, wet with blood, that is surely fresh and in season like sweet-fish on a skewer.

Avenger: "Uhh... You doing a good job of exorcising that demon?"

Caren: "No, I'm not okay at all. I have performed many exorcisms before now, but I have to admit this one is a first for me."

Avenger: "Hmm... So this is a tough one."

Red blotches surface on her bandages.

Luscious. Raw. I had thought this woman was like a doll, but I'm actually looking at raw, succulent meat."

Caren: "In terms of strength, it would be among the weak.

But there is one thing different about it, and that is throwing me off.

...I mean, this demon is harsh with me."

Avenger: "Huh? Doesn't it go without saying that demons are harsh?"

Caren: “No. On a fundamental level, demons are kind. They are an imaginary element that understand one's pain and attempts to remove it. Depending on your perspective, they can be seen as allies of humans. No matter what happens, they will never rebuke a human.”

Caren V (H Version, don’t worry it’s brief.)

To an aberration, intimation is that kind of thing.
To rip out her insides(↑ Soul), and to drive my own life force(↑ Soul) in there. Not to switch them around, but to stain her completely.
A sexual act beginning with the desire to destroy that human being.

In the case of a creature that only knows hate———I guess you could call it lust.

Caren V (Vita version)

ーーーーー I pierce the white flower's throat.


I sink my fangs into her neck and feast upon her soul. I'm not even lucid, but I can feel the magical energy flowing in through the fangs biting into her flesh. The feeling of her body in my arms isn't bad either. Hah, they're both better than I expected.


Resistance and shame was mixed in with her breathing. It's quite a girlish response, but that's not what I'm after.
All I want is her magical energy, and that's the only reason. All I want is her despair, and I want to break her for no reason.
It's fine either way. It's time to devour the prey before my eyes.

I make contact with her soul, and force her to supply me with her magical energy, or snatch it away from her. A normal human would be drained dry by this point, but just as I had expected, she's gotten away with labored breathing. Even though the agony she's experiencing is easy enough to kill her. Quite the self-sacrificeーーーー

To an aberration, a kiss is that kind of thing.
To rip out her insides(↑ Soul), andー
An act beginning with the desire to destroy that human being.

DDD Chapter 2 - HandS (2005-11 for SIDE-A, 2005-12 for SIDE-B)

(was released in Faust magazine)

Character Material (2006-08-20)

Mr. Dawn

In the Holy Mother's prophecy, Dawn will exorcise three demons within his lifetime, according to divine revelation.

He is the only one from the church to exorcise a fully-formed victim of demon possession.

Full Translation of that entryopen in new window

Kaie Karyou

It's said that if God is flawless because of his almighty power ーーーーー demons must be formless because of the incompetent minds of humans.

Full Translation of that entryopen in new window

DDD Volumes 1, 2 (2007)

(was released, like I mentioned before. I am going to translate all of DDD at a later date.)

Q: In Nasu's work (Kara no Kyoukai, Tsukihime, Fate, DDD) Who's the top three strongest characters?

A: Magical Amber, Neco Arc, and Tiger. Well, not really.
Seriously, it's Arcueid, 「Shiki Ryougi」, and The Original Demon. (Not counting Servants)

TL note: You could translate this more excitingly as "Primordial Demon", it's up to you. It's very hard to pin down a translation for this one because it's only a name drop.

DDD - Outside the Universe (2010)

(was released)

Fate/EXTRA CCC (2013-03-28)

(was released, contains demon lore but I will probably translate at a later date.)

Fate/EXTRA Material (2013-08-16)

True Demon

Even in the EXTRA world, the concept of Demons is the greatest obstacle (^ disorder) of humanity; if God is omnipotent and omniscient, Demons are existences of the incompetent minds of humans.

The concept is within our reach, but it is an abyss we will never understand.

In Stay Night, there are no Demons. Only fakes.
Humans cannot stand a chance fighting against the genuine, Incarnated Demons.

(※ There is only one recorded example of an Incarnated Demon being banished, but that is another story.)

Generally, Demons are said to possess human bodies with the intent to incarnate. However, the human mind that has become the seed-bed is unable to endure the strain, and so the Aberration usually self-destructs and disperses its influence into the surrounding area.

Among them, there are those who cease to be human through their own Karma, and as a result, they end up included within the category of Demons despite being human to begin with. This transformation into an Aberration is referred to as becoming a "Fiend". However, they are not True Demons.

In the EXTRA world, whether it be through a human who has been possessed by a Demon, or a Fiend who has lost their humanity through their Karma, as of the current year 2030, there has not been a single successful example of any phenomena that would bring a True Demon into the world.

Although they're labelled as Demons and Fiends, their way of being is no different than high-dimensional beings living on different planets, in different civilizations. And that shouldn't be surprising, because no matter where you go in the known universe, they would never be recognized as “human.”
That way of being is the close to the evil gods featured in a fictional mythos that was popular in the 20th century.

In the True End Route of CCC, a certain someone incarnated and had essentially attained True Demon status, but lost their seat as a god due to a clumsy mistake.