Monster girls, also known as mamono or sometimes just monsters, are the stars of the Monster Girl Encyclopedia and its many subordinate publications. While they come in a cornucopic variety of shapes, sizes, and dispositions, in the Monster Girl Encyclopedia world they are all united by an overwhelming love of sex, with supernaturally beautiful bodies to make sure they get it.

Decried as the enemy of mankind by the Order of the Chief God - the theocratic world-church to which the vast majority of humans belong - monster girls' inhuman looks and questionable dating practices mean they really are viewed with dread by most of the other races of the world, even though for the most part their intentions aren't any more sinister than giving the men they capture a really, really good time.

General Features

The monster girls were created as magical hybrids, combining the traditional blood-drinking, skull-crushing monsters of the age of the Former Demon Lord with the sultry, seductive, and sexy succubus race. What popped out the end were creatures that still walk on eight dagger-tipped legs or a million writhing tentacles, but at the same time have rockin' tits and a literally irresistible sexuality. Their monster heritage endows them with superhuman strength and an instinctive urge towards wanton mating, but it also means they have great difficulty with the word "no" - meaning that encounters with human males regularly end in hot, sticky reverse rape.

The habitats of monster girls are as varied as their forms. Some remain in the haunting grounds of their monstrous predecessors: barren wastelands, deep forests, and spooky graveyards. Others make their homes deep under the sea or high on the mountaintops. But, once the monsters were gifted sexy forms and divested of their propensity to murder everything they set their eyes on, inevitably there are some humans who are happy to live alongside them in mixed communities. Here monster girls are generally more placid, and prove enthusiastic workers in roles from high-class prostitute to... err... other varieties of high-class prostitute.

As the above suggests, not all monsters are violent in their endless pursuit of coitus; different species' behaviors run the whole gamut from one-sided kicking and screaming violation through equitable human-style courtship all the way to enticing men to rape them. Still, whatever method they use, if a monster girl spots you, you are unlikely to come out of the encounter with your pants intact. Not even gender will necessarily save you - many monsters enjoy yuri raping women almost as much as they enjoy raping men. So while monster girls won't club you to death and suck the marrow out of your bones like their progenitors did, if anything they have become more dangerous to other races now that sex has been honed into a superweapon.

A Succubus' Plan: Monsters become Monster girls


Monster girls are obsessed with dicks to the extent that they are obsessed with things that look a bit like dicks

When the world was created by the original Chief God, monsters were slavering, shambling horrors that fed on the flesh of man. The history of the world is an eternal cycle of rise and fall: monsters pillage human civilization when it is weak, and are pushed back to their dark lairs when it is strong. It was a yin-yang balance that ebbed and flowed for uncountable eons... until one being - not a god or even a human, but a monster succubus - had an idea. Succubi were odd creatures by the monsters' standards, as they fed on semen instead of blood, so their lives were dedicated to pleasuring human males rather than ripping them to pieces. And the succubus' idea was: if all the other monsters were like succubi, then there need be no more endless slaughter.

It was a crazy utopian pipe dream which actually could be - and, in the end, was - realized. The succubus teamed up with (and married) a sympathetic human hero, and went on to have herself crowned as Demon Lord, the demigod of the monsters. Using the magical power of that office she cast a great enchantment, which channeled her succubus traits into all the other monsters in the world - and thus monster girls were formed.

It is not a solution without teething problems. Major, potentially-wipe-out-all-sentient-life-in-the-world problems. The most obvious one is that the gods are not especially amenable to upstart mortal sex-demons unilaterally editing the whole metaphysical character of their world. By this point, however, the Demon Lord had grown strong enough that (with her husband's help) she could actually hold her own in battle against the Chief God. Astonishingly thwarted in her attempt at a decapitation strike, the Chief God has retreated to Heaven and settled back into a long game of holy war, directing her mortal and angelic servants to battle the monster girl menace wherever they find it.

A more slow-acting but probably more dangerous problem is that the Demon Lord's monster girl-making enchantment didn't actually do what she'd intended it to. The sexy, pro-active monsters are all according to plan, but the eventual product of all this sex turned out to be only female children. Monster girls give birth to more monster girls, whereas the Demon Lord had expected an issue of monster daughters and human sons. Obviously, this is a feature that leads first to demographic imbalance and later to total extinction. The Demon Lord therefore spends most of her time locked away in her castle with her husband, trying to build up enough sexual energy to cast a second enchantment that will allow monster girls to produce sons.

Common Traits

Although different species of mamono vary far and wide, there are a few traits that are known to be common to many species.


  • Husband Hunting - As stated above, all mamono require human men to have children. Each species has its own particular method of getting a husband, ranging from simply abducting and then raping them to proposing in a similar manner to regular humans.
  • Desire to Mate - Due to the power of the demon lord (who is a succubus), all mamono have a strong desire to have sex implanted deep in their minds. Although some of the more intelligent, docile, or refined species may be able to hold this desire back for long periods of time, they will eventually be overcome by it and be consumed with lust.
  • Submissiveness - Although rare, some types of mamono will obey a human male once certain conditions are fulfilled. Thus far, there are three known ways for a mamono to become submissive.
    • Taming - This method basically involves training them in a similar fashion to animals.
    • Defeat in Battle - Some mamono (such as the werewolf, orc, or ogre) will acknowledge a human man as their master after losing to them in a one-on-one battle.
    • Instinct - Some mamono (such as the dragon or khepri) will instinctively obey their husbands after acquiring them.


  • Overwhelming Abilities - Most mamono have some type of ability (physical, mental, or supernatural) that allows them overwhelm a human man.
  • Lesser Succubus extra art

    A human woman after transforming into a lesser succubus

    Transformation of Human Females - Some mamono are capable of changing human females into mamono through the use of some technique. There are two variations of this trait.
    1. Same Species Transformation - In this process, a human woman is transformed into the same species or a subspecies of the mamono that transformed them. Some of the more well known examples of this transformation are:
      • The succubi, who pour demonic energy into human women through sex. After which, the woman will become a lesser succubus and eventually transform into one of several type, depending on the conditions present (amazoness, kunoichi, etc.).
      • The werewolf, whose bite will transform human women into other werwolves.
      • The apophis, which injects venom into women, transforming them into her lamia servants.
    2. Alternate Species Tranformation - In this process, a human woman is transformed into a different species of mamono. In most cases (such as the anubis and the mummy), the species that the woman gets transformed into is subservient to species that transformed them.
  • Demonic Power - Having been transformed into their current state by the new demon lord, all mamono have a certain degree of demonic power in their bodies.
  • Incubus Transformation - During intercourse, some mamono tend to release demonic power into the man they're having sex with. Over time, that power will transform the man into an incubus. It should be noted that the type of mamono(s) that transformed him will determine what abilities he will develop, as well as his status in their relationship.

Book Information

There are more passages in the Monster Girl Encyclopedia books that describe monster's general features than any other topic. In addition to the few below, see especially All for the Sake of Sex, Races of Monsters, Encounters with Monsters, Fundamentals of the Monsters, etc.

Monsters (Early settings info)

Monsters. Many of them are under the Demon Lord's command. They're all lumped together as monsters, but there exist various races with various forms and traits. They're almost all entirely having a form like that of a human woman, and only the existence of females has been confirmed. Their temperaments and dispositions vary dramatically depending on the race, but fundamentally, they are more instinctual than humans, and many of them are consumed by lust and pleasure. Since only females exist, they need to copulate with human men in order to make children. Since some of the monsters feed on what humans, especially men, possess within their bodies, a vital energy known as “Spirit Energy,” they need to copulate with human men to get it. In this way, human men are essential to them. They possess a variety of abilities to get human men. Most of the monsters have an instinct to attack human men and forcibly have intercourse. For the sake of their own lust and desires, they'll often use coercive measures especially if it's something involving human men. Even if a man they've personally targeted tries to reject them, they will probably use various means such as coercive sex, seduction, spells, and drugs to try and get him. Compared to humans, they possess long lifespans (Depending on the race, it varies significantly, with some living just a little longer than humans, and others living for thousands of years.). Generally, they possess higher physical and magical abilities compared to humans.

They are regarded as “the enemy of humanity” by humans, mainly by followers of “the order.” Humans taken away by monsters never return (Because many of them start living with them in their homes.) It is sometimes said that the monsters “kill and eat humans,” but in actuality most of them are generally friendly towards people. Since they can't live without human men, to them, eating people or killing people is unthinkable.

Also, some monsters have the power to change the women of humans and other races into monsters. In order to increase their allies, they also aggressively assault women.

Concerning Monsters (MGE-1)

At present, due to the influence of the current demon lord, a succubus possessing tremendous power, all of the monsters have forms like that of either an extremely beautiful, or cute human woman.

Their forms are highly varied, running the gamut from being hardly any different from human, to only having the upper body of a woman, with the lower body of a serpent, fish, spider, etc., features of a beautiful, alluring human woman mixed with grotesque traits. Presently, as is visibly apparent, all individuals are female; a male has never been observed. Most of the monsters are more instinctual compared with humans. Their thoughts and actions are all based on desire and dedicated to the pursuit of pleasure. Compared with humans, many of them have greater physical or magical capabilities. They have various special abilities that humans do not possess. Intelligence varies greatly depending on race, but all of the monsters are at least smart enough to have a command of language. It is possible for them to converse with humans. They have long life spans compared with humans. (It varies depending on race, from only a little longer than humans, to those who live for thousands of years.) No matter how old they get, their forms remain young and beautiful, and they never physically age any further than that.

The concept of monsters (Fallen Maidens)

Monster is a general term for various races that are reigned over by the Demon Lord.

Formerly, in the age when the old Demon Lord ruled the monsters that is called “the age of the former Demon Lords”, monsters were grotesque creatures that devoured humans and spread death. However, since an immensely powerful succubus took over and became the new Demon Lord, we've entered an age called “the new Demon Lord's age”, and the monsters forms have changed dramatically. All of them now have beautiful, alluring figures resembling human women. They attack humans, just as they did when they were grotesque creatures, however the meaning behind it is completely different.

The monsters of the present have been heavily influenced by the nature of the Demon Lord who is a succubus and their main food is the same as that of the Demon Lord, living energy called “mana” that is contained within the semen, saliva, etc. of human men. Also, just as it appears, all of the monsters are female. Presently, a male monster has never been confirmed. For that reason, when they reproduce, they must have sex with a human man. And more than anything, in general, all “monsters” are lustful, and instinctual. They are devoted to pleasure and desire, especially the desire to have sex with men. Due to these goals, they coercively have sex with human men, and attack them in order to rape them.

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