Tentacle Monster

The Tentacle Monster is a category of liminal species that is defined by their highly aggressive sexual appetite and their possession and use of tentacle appendages. While exceptions do exists, tentacle monster species are largely considered apex predators, are sexually predatory and completely alien in physical appearance when compared to the typical human form.

Commonly apex predators due to the versatility of their bodies, there is only a handful of biological and spiritual species immune to being preyed upon by tentacle monsters. Tentacle monsters are greatly feared for their ability to use sex, sexuality and a creature's biological base instincts for sex, against their prey. Due to this they are greatly detested and feared by close to all beings, and female beings in particular although tentacle monsters do prey on male beings as well. Even apex predatory species like Arachne and Devils can become prey to tentacle monsters and so actively fear and avoid interactions with them. Some tentacle monsters can also prey on ghosts and spirits (beings that are normally immune to biological predation) and possess specialized appendages capable of interacting with spiritual energy, ectoplasm and mana.

Typical tentacle monsters use their limbs to ensnare and restrain their prey. Once their prey is restrained, the monster will then proceed to use their limbs to seek out, probe and penetrate the various orifices of the prey's body for varying intents and purposes. Penetration is usually non-consensual and involuntary for the prey (although some "prey" do seek out interactions with these species of their own violation and encourage the penetration of their orifices with full consent). In frequent incidents, the prey's initially non-consensual attitude changes during the interaction with the monster into active consent as the tentacle monster manipulates their libido and primal instincts for sex. If unchecked, this results in the prey succumbing completely to their own libido and forgetting their instincts for self preservation which results in them consensually continuing their interaction with the tentacle monster up unto their death or until the monster is done with them. This makes the tentacle monster both the most feared and most desired predator amongst liminal species.

Physiological Attributes

 * A tentacle is basically a flexible mass of muscle and as such can impart a lot of force. When used for combat tentacles can be used to grip and throw objects at people or wrap around and strangle them. Strong tentacles can even be used to impale people or crush them. They may also be used as (somewhat oversized) whips or bludgeoning weapons.
 * One of the reasons why Tentacle Monsters have sex with their prey may be that the process of being incited to orgasm typically tires a prey out and so the monster will continually incite the prey's body into orgasming until it becomes too tired and weak to fight and allow the monster an easier time to eat them, feed from them, mate with them, or otherwise enact their will upon them, being penetrated and brought to orgasm also distracts the prey from what the monster is doing to them. Additionally, large amounts of pleasure sustained for large periods of time may "break" the prey's mental cognitivity, rendering them completely docile or allowing the monster to otherwise warp their mind into being compliant and open to the monster's will.
 * For other tentacle monsters the penetration of their prey's orifices is not sexual at all but is simply a means to gain access to and feed on substances held within the prey's body such as sperm, ovum/eggs, milk, urine, feces, or chemicals and endorphins emitted by the brain (predominantly accessed via the ears but can also be accessed via the mouth, nose and/or eyes). Some monsters even desire to gain access to the contents of a prey's stomach and will do so by penetrating the mouth, anus or navel.
 * Other reasons for penetrating their prey's orifices may include as a simple means to gain a better grip of their prey and render them immobile, or a means to enter their prey's body for physical amalgamation or to gain access to an internal organ, body part, or their soul for acquirement or for feeding.
 * Penetrating orifices may also be a method to kill their prey; Either via asphyxiation (by inserting a tentacle down the victim's throat to block the air passage), internal impalement (inserting a tentacle into the navel, urethra, vagina or anus and continually penetrating into the body, rupturing any organs along the way, until it exits out via the mouth, or in through the mouth and out via the vagina or anus), precise impalement (such as penetrating the ear or nose canal to impale the brain or penetrating the vaginal canal to gain access to and impale the heart hidden within the rib cage) or in preparation to rend the prey's body apart by inserting as many tentacles in as many orifices as possible and then continually pulling outward in opposing directions until the prey's flesh exceeds its capacity to stretch and tears away from its skeletal structure. To a similar end a tentacle monster can also penetrate a prey's orifice with a tentacle too large (or increase the girth of a tentacle the prey has already been penetrate with until it is too large) to naturally fit the prey's body, forcing the prey's body and flesh to tear around it as the monster continues inserting the tentacle inside them.
 * Yet another option a tentacle monster can use to kill their prey is to use their penetrating tentacles to inject the prey with hazardous substances (eg. acidic sperm, digestive acid) or hazardous amounts of substances (amounts that cause the prey to drown or their body to exceed it's physical constraints and burst). Sometimes these substances incidentally act as the monster's sperm or ejaculate but the prey is physically incapable of handling the substance injected within them (due to cross-species incompatibility) and they die from the experience.

Genre History
The tentacle monster's prominence in Japanese erotic literature largely arose due to influence from the aesthetics of censorship in western civilisation.

One of the earliest examples of Tentacle Monster erotica is a shunga illustration (erotic artwork that was commonly accepted as non-taboo in Japanese life) from the 1814 novel Kinoe no komatsu; popularly known as  where a Japanese pearl diver is depicted being captured, enveloped and forced into receiving cunnilingus from one octopi as another gropes and kisses her. While western audiences often interpret Hokusai's illustration as rape, Japanese audiences view it as consensual, particularly as the dialogue in the illustration shows both the diver and the two octopi expressing their enjoyment with the situation; with the large octopus exclaiming its delight in finally ensnaring her, complimenting how "ripe and full" her "bobo" is and expressing his desire to drag her beneath the ocean to the Dragon Palace to envelop her, while the diver herself exclaims how pleasurable being sucked by the octopus is and encourages the octopi to touch her and continue "sucking at the mouth of her womb" as she orgasms. The Dream of the Fisherman's Wife is not the only work of Edo-period art to depict erotic relations between a woman and an octopus. Some early carvings show cephalopods fondling nude women.

In the late 19th century (1882) Joshua Handley, an English artist and photographer for erotic literature in Paris, traveled to Japan to document the less well-known aspects of the Japanese and their culture. This resulted in him viewing the Dream of the Fisherman's Wife and forming an obsession with cephalopod erotica. Handley attempted multiple times to publish illustrations similar to Dream of the Fisherman's Wife in England, even coming up with some of his own involving female pearl divers, shipwrecked gentlewomen or unwary bathers who would fall prey to an octopus and become enmeshed in its tentacles, however, his publisher was appalled by the content. Not by the tentacles and rape (which they believed would appeal to people with "darker sensibilities") but at the notion that the women in the stories actually enjoyed themselves as they succumbed to tentacles and suckers. Handley eventually gave up trying to produce his artworks and, ashamed of his tastes, abandoned all involvement with pornography and turned to illustrating children's books under his mother's maiden name.

As part of the Meiji Restoration (1868-1912), which saw Japan adopt many aspects of western civilisation in order to "become more civilised", Japan adopted new laws influence by Victorian-era Europe to forbid public nudity (where previously Japanese men and women were free to walk around topless or in loin-cloths should they wish) and multi-gender public baths. During this era, creation of traditional Shunga art was also restricted.

Restrictions increased further during the years surrounding World War II, forbidding all erotic art and literature, until post-WWII when the occupying Allied Forces imposed a number of reforms on the Japanese government; which included a lessening on restrictions of erotic expression. Due to this, while “obscenity” (which included depictions of exposed genitalia) was still illegal to portray without censorship (which led to the creation of the "Black Bar" and "Mosaic Blur" to censor the offending material), the diversity of sexual acts that were now permissible to use led to a rise in erotic fiction.

By 1990, in their pursuit to create new material, erotic artists had devoted their efforts in creating new ways to either circumvent the "obscenity law" or to otherwise eroticize otherwise banal subjects, however, it was artist Toshio Maeda who is credited with coming upon the notion that, while the law forbid depicting traditional human genital-to-genital intercourse, it did not forbid depicting pseudo-genital-to-genital intercourse. Following this revelation, Maeda creates a new erotic manga that depicts women in sexual situations with non-human creatures who use tentacle-appendages to penetrate and otherwise assail the female characters. As the monsters did not have a defined gender and did not have/use human genitals (as they are strictly defined by the law), the sexual acts could be shown uncensored. Furthermore, the diverse sexual utility that these fictional creatures brought to the conceptual table meant that numerous fetishes could be believably implemented at the same time.

The earliest animated form of tentacle assault was in the 1985 hentai OVA, though the scene in question was removed when the OVA was re-released in a non-hentai form. The first non-hentai anime production portraying tentacle assault was the 1986 anime OVA, which featured a female Chronos soldier named Valcuria being enveloped by the 2nd biological Guyver suit when the suit produced tentacles to fuse with her, finding and penetrating all of her orifices in the process.

Toshio Maeda produced 1986's, which popularized the trope of tentacle rape and featured a scene where a nurse gets torn apart by the tentacles assailing her which grew to serve as the template for tentacle rape scenes. In 1989, Toshio Maeda's manga Demon Beast Invasion created what might be called the modern Japanese paradigm of tentacle porn, in which the elements of sexual assault are emphasized. Maeda would go on to create 1992's and 1995's, both of which are additionally considered staples in the Tentacle rape genre.

The use of tentacles in live-action films started in American B-movie horror films and has since migrated back to Japan. Producer Roger Corman used the concept of tentacle rape in a brief scene in his 1970 film and he would again use tentacle rape while producing  in 1980. The scene was so graphic that the film's director, B. D. Clark, refused to helm it and the actress whose character would become the victim refused to do the full nudity required, so Corman directed the scene himself and used a body double for some of the more graphic shots.

Trivia

 * The tentacle monster is a source of great amusement for the anime/manga fandom, is often brought up in a joking manner and is subject to much parody from inside and outside the anime community. Unfortunately, it is also used by those outside of the fandom to exemplify anime and manga (and those that enjoy them) as being a perverse and inappropriate medium.
 * For some men and women the fetish appeals to those who enjoy seeing men and women being subjugated and mated by something that isn't human. Some cultures consider animals to be more sexual than humans; for example, the fact that most animals conceive more easily than humans, give birth faster/more easily and have more offspring, leads to the belief that animals (and by association, non-humans) are sexually superior to humans and so the notion of a non-human engaging a human in sex arouses our base instincts that drive us to mate with superior beings to produce stronger offspring. Due to this instinct, people wanting to experience sexuality on a deeper, wilder level are turned on by the non-human's combination of grace and power, their inhuman wildness, and their exoticism. As tentacles are one of the most inhuman appendages on animals, beings and animals possessing such limbs arouse these desires. "It's the physicality of tentacles, soft, flexible, fully controlled, and the multiple uses for suckers are mind-boggling. Mixed with restraint fantasy and the idea of total immersion in the sex. The tentacles are arms, that caress but they're also covered with suckers. Flexible arms that caress, covered with countless pseudo-mouths to suck and kiss - it's a powerful sexual image. Some do not like the rape fantasies but I love the idea of so many arms and mouths and hands all in the same limbs, all over my body doing things that no human can."
 * No doubt possessing a domination-submission component, the fetish also runs parallel to group sex fantasies where the person desires to be wanted by multiple persons and pleasured by multiple appendages at the same time. Women who enjoy the fetish have admitted that they imagine it'd be quite stimulating to have the multiple orifices of their body pleasured at once, while having their entire body continually caressed while doing so, without unconsciously comparing themselves to them (as they are not human) and worrying what they look like or whether the monster is going to call them in the morning that they experience in human society. Some enjoy the rape aspect and the notion of being in no way in control of what happens to them (notions they fear in real life), of their body being taken advantage of and possibly impregnated or consumed by the creature. The emotional freedom that this brings allows for them to release the stresses of responsibility that they experience in real life and just enjoy the sex.