An incubus is the male counterpart to a succubus, and represents the fate of (most) males exposed to high levels of demonic energy. Unlike female monsterisation, where the physical and mental change from human to monsters is rapid (in some cases taking only moments [1]), for incubi the process is much more gradual and open-ended. Just as monster girls become more and more powerful the more sex they have, so do incubi, with increases to lustiness, physical attributes and lifespan [2].

Incubi are said to be "an ideal male to a female monster", therefore many monsters are eager for their mates to transform faster so they can enjoy the changes. Monsters with a lot of demonic energy at their disposal, like dark matters or khepri, are noted as being able to effect the change quickly, but the majority of monsters must just rely on lots and lots and lots of sex. Certain items which can expedite the transformation, like Succubus Nostrum, may be sought by eager wives.

Although the vast majority of information on incubi pertains to human men, elves can definitely become incubi [3] and there seems no reason that any of the few male dwarves left can't do so as well (or rather that they didn't already become incubi some time ago), as dwarf men are also considered a type of human.

A Being That's Convenient For MonstersEdit

Refer to: Fallen Maidens; The Incubus

Physical changesEdit

The biggest changes of all occur in the functions that are also most important to monsters that get used during sex. It depends on the race and preferences of the monster that one is coupled with, but most men who become an incubus will have their penis grow larger by leaps and bounds, and they'll be able to please monsters even more. The amount of semen and spirit released from there will be incomparable to when they were human, and they'll have boundless stamina so that they're able to release it again and again without getting exhausted. [4]

Besides genital gargantuism, incubi do not receive (permanent) drastic physical changes comparable to, say, an arachne's abdomen or a succubus' wings and tail, although their eyes may change color due to demonic energy [5] (the source for the eye color change is not canon). They do, however, see away features that impeded their sex lives previously, like corpulence or the general frailties of old age. And as the time spent with their monster partner increases, Incubi find their appearance and even their apparent age adjusting to match their wife's taste: "It could be as a boy, as a young man, or as a mature man". Since this happens simultaneously with the man's tastes reshaping her [6], eventually both monster and incubus will gain their spouse's ideal fantasy body.

There are changes under the skin for an incubus too. Stamina increases to monster-like levels as the eldritch power of demonic energy suffuses their body, and incubi gain some measure of the environmental resilience of their monster partner (e.g. heat resistance for a lava golem's mate, breathing underwater for a Sea Bishop's mate, night vision for the mate of nocturnal or cave-dwelling monsters[7]). Like a succubus, they also gain the ability to actually sustain themselves on their partner's spirit energy in place of food.

An exception to the lack of drastic changes are the husbands of the various chaos/abyss-aligned monsters (such as atlach-nacha and mindflayer), which gain the ability to change into completely non-human or only vaguely humanoid forms. These forms can be reverted to normal human form at will, at least after the initial forced transformation, and thus are not considered a permanent transformation.

Mental changesEdit

On first being attacked by a monster girl, humans are likely to be consumed by an instinctive fear and revulsion at their demonic appearance. Such atavistic terror and Order moral objections are thrown aside with the transition to an incubus: Their thoughts and values change, all becoming centered around having sex with monsters [8]. Lust skyrockets to keep pace with the monsters' insatiable hunger for sex, and their interests in other things (like work and hobbies) decrease, as sexual activity becomes a more important part of their lives:

Also, after being completely charmed by a monster, one's aesthetic sense will have changed so that he feels that the grotesque parts and organs of monsters are beautiful. Other than that, one's sense of time, and values concerning work and recreation will also change so that it becomes more convenient to live with monsters.[9]

Incubi never get bored of sex or lose the mood after doing the deed; they just keep going. Whereas a human first being attacked by a monster is likely to pass out from pleasure before his rapist is close to being finished with him, incubi flip the dynamic on its head and "end up being unable to be satisfied, unless he has sex with all of the monsters in his harem".

Magical changesEdit

When women undergo monsterisation, their spirit energy production ability (which is weaker than men's to start with) gets extinguished entirely and they become a creature with only Demonic energy inside them. The same does not occur with men and incubi, instead there is a large improvement in mana production in response to increasing amounts of Demonic energy within their bodies.

The Demonic energy that enters a man, "marks" an incubus with his partner's uniquely scented Mana. Whether other monsters chose to respect this implicit marking of territory is down to their personal tastes; unicorns and cancers could be discouraged, while beelzebub and bicorns have the opposite reaction. Although human women can't detect it, the demonic energy can have a drastic effect: if an incubus has sex with a human woman, his semen will monsterise her.

Daily livesEdit

Although the sex drive of a man who has become an incubus is greatly enhanced, causing sex with their monster partner or partners to be a greater part of their life, incubised men are still free to pursue previous hobbies and work from before incubisation. This often results in monster nations exporting produce to other nations, sometimes producing goods that can only be created by a monster and her husband, or are only available in Demon realm lands.

A large cultural shift has begun amongst the monsters more recently, with monster wives taking a keener interest in more human activities, whether it be culinary or a craft. Many of these changes have occurred as monster women have sought to improve the lives of their husbands, helping to keep them happy. Many single monster women have also taken up crafts to further impress potential mates, instead of directly assaulting them.

True Nature Edit

In World Guide 3, the baphomet Runya Runya shares convincing arguments that incubi and heroes are essentially the same type of being. That is, they are humans that have broken the "shackles" that are thought of as human limits, the only difference ultimately being that where heroes have their shackles broken by divine power (or sometimes other sources of energy), incubi utilize demonic energy to remove their limiters. The powers and/or abilities they gain after breaking these shackles (aside from spells and abilities specifically dependent on gods or monsters) are their own, and remain even if (for instance) all divine power is removed from them. Heretical theologians theorize that humans were created as beings with unlimited potential (that was for unknown reasons and by unknown parties later shackled), and that rather than becoming a new type of being, heroes and incubi are merely regaining the abilities they were meant to have all along.

Further evidence for the lack of meaningful distinction between heroes and incubi can be seen in how most every ability (including sexual ones) gained by incubi can potentially be gained by divinely blessed heroes and vice versa. Notably, humans blessed by Eros to become her version of "heroes" gain (among other things) sexual abilities on par with incubi.

Research into all this however is forbidden by the Order, and thus monsters and monster-allied humans seem to be the only ones studying just what heroes and incubi really are.

Book InformationEdit

The Incubus (Fallen Maidens, p77)Edit

An incubus is mainly a human man that kept receiving Demonic mana, and containing it within his body, resulting in a transformation into a being that's convenient for monsters, possessing superhuman stamina and lust. Under the current concept, monsters are all female beings that only possess Demonic mana, so an incubus, which is male, and possesses both mana and Demonic mana at the same time, is not a monster. Ultimately, they're just humans altered by Demonic mana. However, the Order regards them as being the same as monsters, and they're targeted for expulsion and suppression.

1. Until Changing Into An Incubus

Compared to monsterisation, in which changes suddenly appear, changes caused by incubisation are extremely gradual. Unlike a woman's monsterisation, where they totally change into a monster both mentally and physically after having sex one time, the changes that occur when a man transforms into an incubus and afterward, appear bit by bit each time he has sex with a monster.

Human men transform into an incubus by having sex with monsters, and having Demonic mana poured inside of them. Unlike women, who recover mana by absorbing it from the air, men continue to produce mana within their own body, so compared to women, it's more difficult for Demonic mana to take hold, and they do not change into an incubus just from having sex once.

In the case of the succubus family of monsters, they possess “succubus' energy” which has a higher retention rate, and causes men to release more mana in a single session of sex by infusing them with it, so compared to other monsters, incubisation is extremely fast, and in the case of a powerful succubus, it's even possible to change a man into an incubus by having sex once.

Also, even if it's a monster of another race, after spending a long time as their husband, and living beside them, by continuing to have sex, Demonic mana gradually takes hold in the body after each time, and eventually, a man will transform into an incubus.

Additionally, even monsters not of the succubus family can accelerate the incubisation process by continuing to ravish a man with multiple monsters, and aside from that, there is “succubus' secret elixir”, a medicine made from succubus' energy, and there are special rituals and spells that can be used to quickly change a man into an incubus.

When transformation into an incubus occurs, it's not like one can clearly tell that he's transformed, as was the case when a woman is monsterised. In the case of monsterisation, a woman is able to grasp that she's become a monster because of the changes in her body, and a feeling of ecstasy like she's been reborn, but in the case of incubisation, before one knows it, he's already changed into an incubus.

In the course of getting continuously violated by monsters over and over, a man who at first would tire soon, exhaust his mana, and pass out, will steadily increase the amount of time he can have sex, and the number of times he can release mana increases. In the beginning, the pleasure is so violent that one can't even think straight, but one gradually becomes able to enjoy the pleasure. Gradually one will change so that he can't help but consider having sex with the monster in front of him, and gradually, he'll come to desire to be ravished by the monster before his eyes. In this way, bit by bit, one will change into an incubus without being aware of it.

What makes an incubus an incubus, and a man a man is the mana within his body and the existence of a mana production faculty. Very rarely among the incubi, there exist those who unconsciously destroy their own mana production faculty. In that case, mana will not be produced, and the body of an incubus who loses mana and is completely ruled by Demonic mana will completely change into a monster. This monster is called an “Alp (encyclopedia – p. 108). The process of changing into this monster is described on p.92 of this book.

2. Mental and Physical Changes Caused by Incubisation

As for changes caused by incubisation, the changes that appear basically make it convenient for the monster that one is coupled with.

First, it is purported that the looks almost don't change at all compared to when one was human. Monsters don't care very much about the attractiveness of a man's face, so in most cases there are no changes whatsoever. The body changes to become more healthy and durable so that it's convenient for sex, but it's rare for the appearance to change greatly other than that.

A rare exception occurs and the appearance greatly changes in the case of those who are too feeble or fat, and their form will be vastly improved so that it's convenient to have sex with monsters. Also, in the case of those who are so old that it's a hindrance to sex, they will also be rejuvenated.

After one has changed into an incubus, the mind also changes so that one's values become nearer to those of the monsters, but compared to monsterisation, even if only a little bit, human-like values from the period when one was a human will remain. However, the values and thoughts of an incubus, a being that became a monster's prisoner so much so that it altered the nature of his mind and body, will change to become eager to have sex with monsters. One's lust will swell up like that of the monsters, and disgust towards monsters and sex, etc. will have long since disappeared, and one will change so that he aggressively desires sex with monsters.

Also, after being completely charmed by a monster, one's aesthetic sense will have changed so that he feels that the grotesque parts and organs of monsters are beautiful. Other than that, one's sense of time, and values concerning work and recreation will also change so that it becomes more convenient to live with monsters.

The biggest changes of all occur in the functions that are also most important to monsters that get used during sex. It depends on the race and preferences of the monster that one is coupled with, but most men who become an incubus will have their penis grow larger by leaps and bounds, and they'll be able to please monsters even more. The amount of semen and mana released from there will be incomparable to when they were human, and they'll have boundless stamina so that they're able to release it again and again without getting exhausted.

The quality of the mana is also remarkably different. It becomes so much thicker, stickier, and sweeter, that it's incomparable to when they were human, and one lick will make a monster melt. Also, human men sometimes lose the mood after expelling mana, but it doesn't occur in an incubus, and their lust for monsters just flares up.

In addition to the normal food that they ate when they were human, it's also possible for an incubus to feed on Demonic mana by having sex with monsters. For that reason, an incubus never gets exhausted when having sex with a monster. Instead, their entire body will brim full of lust and energy due to Demonic mana. When the body of an incubus obtains Demonic mana by having sex with a monster, it will immediately produce mana. When this mana is released to a monster, the monster will produce Demonic mana from it and pour it into the body of the incubus.

Astonishingly, with this cycle, not only does the total amount of magical energy not decrease, instead it continues to increase, so it's possible for a monster and an incubus to keep having sex almost forever, and as long as there's one incubus and one monster, it's possible for them to live by just having sex. As far as the divinities and the Order are concerned, this nearly perpetual cycle is something that is in violation of divine providence that will greatly throw off the laws of the universe, and is extremely viewed as a problem.

Also, it's said that the lifespan of men who become an incubus becomes dramatically longer. Since they can keep living by having sex with each other, their lifespan is roughly the same as the monster that they're coupled with. Just like monsters, their appearance stops aging at a certain stage. It could be as a boy, as a young man, or as a mature man. Since an incubus is a being that's convenient for a monster, they change depending on the tastes of the monster that they're paired with. In this way, an incubus is none other than an ideal male to a female monster.

The power of an incubus grows stronger the more Demonic mana they accumulate. In the case of those that periodically have sex with multiple monsters, it piles up, so in the case of a single incubus that makes a harem of multiple monsters and keeps having sex with them, it ends up causing the birth of an extremely powerful incubus. Regardless of how many monsters are in the harem, an incubus has limitless stamina and lust, and can have sex with all of them. Even if an incubus keeps having sex with them day and night alternatively for a period of several days, he'll never get tired, lose his erection, or feel pain or boredom. On the contrary, he'll end up being unable to get satisfied unless he has sex with all of the monsters in the harem, and it'll even get to the point where it's as if spending several days having sex with all the monsters in the harem is like having sex one time to him.

Additionally, those who become an incubus can also adapt to the environment to match the monster that they're coupled with. For example, an incubus coupled with a monster that lives in a desert, or near a volcanic crater, will gain resistance to heat, and an incubus that is coupled with a monster from a snowy country will gain resistance to cold. They gain such strong resistance that they can even actively have sex with monsters in such environments. To provide a remarkable example, due to a ritual performed by a “sea bishop (encyclopedia I – p. 116)”, there are incubi that became able to live underwater. This ritual is performed to quickly change someone into an incubus, so as a result of having been changed into an incubus with the Demonic mana of the monsters of the sea, they've adapted to live underwater.

Since an incubus retains the Demonic mana of the monster he's coupled with inside his body, a human woman who has sex with an incubus will end up transforming into that race. However, the lust of an incubus who's kept having sex with monsters will not be satisfied by having sex with anyone other than a monster.

Also, an incubus' superhuman lust is only directed towards the monster he's coupled with no matter what, and they don't have an instinct to attack the opposite sex like monsters do. For that reason, incubi do not attack and forcibly rape human women, and such an incident has never been confirmed.

Incubus (MGE-1)Edit


Human men who have been violated by demonic energy, whose nature is vastly changed. They are often also treated as monsters, but technically all monsters are female, so no matter what, the incubi are just humans who have taken their nature from monsters.

Transformation into an incubus

Transformation into an incubus mainly occurs when a man continues to have sex with a monster, continuously receiving her demonic energy in his body. After becoming an incubus, their physical appearance hardly changes at all from when they were human; however, they gain vigor and lust like that of a monster, far exceeding that of a human. Their thoughts and values change, all becoming centered around having sex with monsters. Their body also gradually changes to become more suited to having sex with them. In addition to ordinarily eating food, just as the monsters sustain themselves on spirit energy, the incubi become able to live by sustaining themselves on the monsters' demonic energy Through this, the lifespans of the incubi are also extended to match that of the monster whose demonic energy they use to sustain themselves. Furthermore, both the volume and quality of the spirit energy produced inside their bodies increases by leaps and bounds. They are an extremely convenient existence for a monster. It's probably fair to say that they are the equivalent of male monsters.

By continuously having intercourse with a monster from the succubus family, a man can be transformed into an incubus comparatively far more quickly; however, even in the case of the other monsters, after spending a long period of time at her side as her husband and having frequent intercourse, a man will probably eventually change into an incubus even though the changes are very gradual. Among the monsters, there is a medicine made from the demonic energy of the succubus in circulation that is called “succubus' nostrum.” Many monsters like having their husbands drink it in order to try to change them into an incubus more quickly. Also, the incubi possess the same kind of demonic energy inside their bodies as the monster who changed them into an incubus, and if they have sex with human women, the women will be transformed into monsters.


  1. Fallen Maidens; Monster Transformation Case Studies; 09 Possessions; a decapitated dullahan "had been a human knight until only a moment ago."
  2. MGE-1; Spirit Energy and Demonic Energy; The Various Roles of Demonic Energy
  3. Non-human monsterization: Elves (Fallen Maidens, p96): "Elves are sensitive to magical energy, and at the stage when one has been corrupted by demonic energy, everyone around will notice it, and banish them from the village, so chain monsterization and conversion of elven men into incubi rarely ever happens. On top of this, elves' high spirit energy implies that elven men will require more demonic energy than humans to incubize; but still, it is possible to turn them.
  4. Fallen Maidens; Monster Transformation Case Studies; 00 Incubus
  5. Baphomet Complex: "Big brother was becoming a full incubus now. Even his almost-transparent blue eyes were turning a purple steeped in magical energy, the same as mine.
  6. Fallen Maidens; Relations with Monsters; Monsters that Become Prisoners
  8. MGE-1; Monsterization; Transformation into an Incubus
  9. Fallen Maidens; Monster Transformation Case Studies; 00 Incubus

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