Mindflayer

Mindflayers are subterranean monstergirls that specialize in mind control. They attack both males and females, implanting lewd desires by stimulating their victims' brains through the ears. Women are turned into sex-crazed thralls and sent back into the human world, periodically returning to their mindflayer mistress so she can feed on the memories of carnal pleasure; a process which slowly leads to monsterization. Meanwhile, captured men are kept by the mindflayers to rape themselves, and possibly turned into squid-panties a'la tentacle medicine.

Like the followers of the Fallen God and the natives of Zipangu, the mindflayers first allegiance is not to the Demon Lord. Rumours suggest that in fact they are primarily loyal to the mysterious demons of chaos.

Encyclopedia Entry
Grotesque enchantresses with tentacles growing from their head and lower body who form peculiar societies underground. Highly intelligent and dangerous with an extremely obscene mentality, they possess the power to manipulate the mind. They are of a different mind from even the radical faction of the Demon Lord's army, and although they have been influenced by the Demon Lord, they are not her underlings. According to one explanation; it is purported that they are a race who serve chaos monsters that slumber deep within the depths of the sea, and it is their duty to fill the land with their minions. They appear above ground seeking prey and they will not only target human men who serve as their partners, but also actively assault human women to entice them into becoming the same race.

They seize their prey as if embracing them from behind and slip their tentacles into the prey's head through the ears to directly pour in demonic energy and pleasurable signals. The rational mind and thoughts melt away, and the mindflayer slurps them up. The prey's mind is consumed by pleasure and the watery sounds of the mindflayer's tentacles noisily stirring about inside their head. The prey will be completely helpless and unable to do anything but gasp and moan. If the prey is male, then a lewdly obscene mind suitable for the partner of a mindflayer will be implanted inside his defenseless head. Once a man becomes a being that exists to have sex with a mindflayer, his body and mind will no longer put forth any resistance at all when the mindflayer habitually coils around her husband using her body and tentacles to induce pleasure. Such men will experience joy as their mind is melted and slurped out along with their spirit energy.

On the other hand, in the case that her prey is female, it is said that she won't immediately be converted into a monster, and will instead be released while still human. However, just getting a whiff or the odor of a human man or his spirit energy will be intoxicating, and she'll be unable to maintain her ordinary thought processes. In all likelihood the woman will have been partially modified so that only parts of her memories, values, senses, and perception will be that of a monster. She may have been granted only "a monster's olfactory sense", or she may have been implanted with a monster value such as "taking pleasure in being sexually desired by others", or a false memory such as "becoming a monster and having sex with a man."

While a woman will retain her human body, she will be inflamed with a monster's passion, and learn the pleasure of being a monster. No matter how much she masturbates and has sex, she will never be able to experience fulfillment in her human body, and her mind will be eaten away. She will start to frequently recall the pleasure and watery noise of having her mind slurped, and despite having been released will end up making her way back to the mindflayer on her own. When the mindflayer enjoys herself by sipping the taste of a woman's mind, she will notice that it is changing into something appropriately obscene and befitting of a minion. As if to reward her, she will change the woman slightly closer to being a monster. As these events repeat, eventually the woman will beg to be changed into a monster. Sometimes such women will sexually assault men while still human, in order to show off that they are of the appropriate mind to become a minion. After debauching her mind to such a degree, a woman will finally be accepted as a new "mindflayer".

Also, they themselves are always immersed in the obscene watery noises. Even if they don't have any prey, they will use their tentacles on their own bodies. In order to make sex with their partner more pleasurable and fulfilling, they continually melt their mind and reforge it into something even more obscenely debauched.

The squid-like thing covering their lower abdomen frequently squirms as if it were an entirely separate organism. It is said that they pat it lovingly with tentacles and then it releases white viscous fluid. "Men who become intimate with them are suddenly transformed into squids, becoming stuck coiled around their hips with a tentacle slipped inside their lower abdomen." This has been observed, but even when asked about the truth, the only response of the mindflayers is to smile alluringly.

Kenkou's Notes:
''今回の更新は、「マインドフレイア」さん. ''

This time's update is Mindflayer”-san.

''いろいろと正体不明な魔物で、他の魔物達と異なる恐るべき能力や精神性を有しています. ''

Much remains uncertain about these monsters, and they possess terrifying abilities and a terrifying mentality compared to other monsters.

魔王の影響で女性にはなっているのですが、どうやら魔王の部下というわけではないらしく・・・

They have become females due to the influence of the Demon Lord, but it seems they aren't actually underlings of the Demon Lord...

''というわけで、詳しくは　エロ魔物娘図鑑本文　をご覧くださいませ. ''

And so, for details please check the erotic monster girl profile.

Extra notes via KC's Twitter:
''マインドフレイアに関して補足しておきますと、夫のイカ化は可逆で、好きな時に人に戻ったりイカになったりできます. '' Here is some supplemental information concerning the mindflayer. The husband's squid transformation is reversible, and he can return to being human or change into a squid whenever he likes.

''もちろん人の姿での交わりもするんですが、人前でイカにぬぷぬぷされておきながら、人の姿の旦那と人前でいちゃつくのは恥ずかしｇ、何故か隠そうとするみたいです. ''

Of course they do it in human form as well, but while they are fine with being teased by a squid in front of other people, they're shy about doing it with their husband in human form in front of others, and for some reason, it seems they try to hide it.

''魔王の部下ではないですが、割とﾏｲﾝﾄﾞﾌﾚｲｱは他の魔物と仲良くしてるとか. ''

They aren't underlings of the demon lord, but mindflayers do get along relatively well with other monsters, or something like that.

例えば他の夫婦に頼まれて、夫に「自分はオーク（旧魔王時代」魔物娘に「自分は人間の姫騎士」という記憶を与えて、演技じゃない迫真のプレイの手助けをさせられたりしてるんだとか…

For example, if requested by another couple, she can give the husband the memory that “he himself is an orc (from the era of the former demon lords) “ and she can give the monster girl the memory that “she herself is a human knight”. This does aid in having realistic play that isn't acting, and stuff like that...

Extra Extra notes via KC's Twitter
マインドフレイアは某勢力なので文章を過激気味に書いたけど、実際ヤってる事はゲイザーあたりと似ている感

As for mindflayers, it is an unknown force, so I wrote the text with a radical feeling, but the sense is that what they are actually doing is roughly the same as gazer.

「伴侶への愛がある」は基礎設定であって、本文で強調してなくても確定事項なんだってば！

“Having love for one's partner” is one of the standard settings, and even if the main text doesn't emphasize it, the issue is settled!

Q:「魔物娘の夫に関する認識を洗脳や薬で弄るとどうなる？」

Q: “What would happen if one were to manipulate a monster girl's recognition of her husband using drugs and brainwashing?”

A:''「夫Aの外見や匂いや精の味を間男Bのものに、BのそれらをAのものと認識する様にした場合、何故か夫Aと迫真のNTRプレイを始めたりします. 認識的に夫なはずのBに手を出されると突然洗脳が解けてキレます. 理由はわからない！（続''く

A: ”In the case that Husband A's external appearance, scent, and spirit energy flavor are made to be recognized as partner B's, and B's are made to be recognized as A's, for some reason, she could begin some convincingly realistic NTR role-play with husband A. Despite that she should recognize B as her husband, as soon as B lays a hand on her, she'll snap out of the brainwashing and flip out. I don't understand the reason! (continues)

''ってのを昔ツイートした事がありましたが、マインドフレイアの能力で同じ事をやった場合も、当然同じ事が起こります. そもそもマインドフレイアはそういう事をやりませんが. ''

So that's what I tweeted a long time ago, but also in the case that the same thing is done using the mindflayer's ability, of course the same thing would occur. A mindflayer wouldn't do such a thing in the first place though.

''その場合は夫の不安消しにしか使わなそう. あったとしたらだが、ここまでしてもお前の元にいくんやぞおら！みたいな''

In that case, it seems it would only be used to erase the husband's anxiety. Supposing it did happen, it would be like, “Hey, even if I have to go this far, I will reach you!”

なんだか夫婦向けのカウンセラーの職についてそうなマインドフレイアさんに・・・

It kind of seems like mindflayer-san would be suited for the occupation of a marriage counselor...

Trivia

 * This monster girl is based on the illithid from the Dungeons & Dragons universe. The illithid are more commonly known as Mind Flayers.