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Rachnera, an example of a Arachne.

The Arachne (アラクネ族, Arakune-zoku) are a carnivorous, mono-gendered demi-human liminal race that have a beautiful female humanoid torso but are attached at the hips to the body of a giant spider. They are physically strong, agile, and fast.

According to Killa's secrets, Arachne, like Insectoid Liminals, belong to the group of Arthropod-like Liminals, although, similar to normal spiders and insects, Arachne probably belong to a different phylum than Insectoid Liminals.

Arachne are most noted for being able to create a silk that is five times stronger than steel and twice as elastic as nylon. They can also produce variants of the silk, ranging from sticky, to stretchy, to tough, to suit whatever situation is required. While most commonly used to catch and bind prey, Arachne can also use their silk to form a network of threads to sense vibrations and even outright listen in on conversations at a distance and through windows.


Known for creating "community nests" within dark forests and deep caves and caverns, the Arachne are reputed for being deadly towards humans, famed for using their webs for entrapping men and women and killing them through either eating them whole or biting into their skin and sucking out their bodily juices like a spider. This reputation arose due to the Arachne's natural predatory abilities and form and due to their behaviour of, being a female-only race, luring men to their hidden dwellings and holding them for mating in order to survive as a species; using their webs to restrain the men should they resist. As stories of groups of men being captured by Arachne are rare, it is rumoured that on average multiple Arachne would have to mate with a single male, although it is unknown whether they do so in groups (orgies/threesomes/etc like the Lamia) or individually (with the man being shared/passed from one Arachne to another each night)(Rachnera Arachnera's open bisexual tendencies during sexual play may allude to the former being true). Additionally it is unknown whether the Arachne that captured the male has first rights to mating with/owning them or if men are caught to be shared by the nest (like fishermen catching fish for the village to eat), or if the leader of a given group gets first rights to him, but they mate with all the men they caught.

Since the Cultural Exchange Between Species Bill, government agencies have put a stop to the Arachne practice of luring and kidnapping men against their will (due to being a federal offense), and likely freed any men they had who didn't wish to stay. While this fortunately put an end to the abductions (and borderline sexual assault) of human men, the results were not so positive for the Arachne, who need men to maintain their numbers and produce the next generation. Presumably, the Arachne birth rate has declined dramatically due to this (notably, unlike with the very openly affectionate Lamia, it is not stated that most men the Arachne took ended up agreeing to stay willingly, suggesting the Arachne may have ended up in a worse situation than the Lamia tribes). In an attempt to evolve their culture to become "more open", Arachne nests have taken to sending "expeditionary forces" via the exchange program for the purpose of ascertaining whether or not Arachne and Humans can coexist as equals despite the Arachne's intimidating appearance and generally reticent behaviour and Humanity's tendency to vilify anything different from themselves.

Arachne tend to be prideful and closed off emotionally, being generally against changing their behaviour or "playing nice" to accommodate others, but can be surprisingly empathetic and reliable friends and lovers if someone earns their trust. Even then, outside of being with these trusted friends, Arachne often prefer to stay at home, in the shadows, or away from the busier areas of social gatherings. Rachnera's interactions with her tribe and her own behaviour over the course of the series imply that much of her kind's prickly nature and unwillingness to interact as equals comes down to their own insecurity and fear of being made at all vulnerable.

The Arachne's traditional craft is knitting, which they have honed after repurposing their abilities from typical "web spinning".

Physiological Attributes[]

  • Abdominal Mark: Arachne have a marking on their secondary abdomen and every marking on each Arachne is as unique as the fingerprints on humans.
  • Eyes: The average Arachne has six eyes but the number can vary between species/subspecies or individuals. Arachne can see ultraviolet rays with their eyes and they seem to have excellent night vision.
  • Exoskeleton: Arachne bodies are covered by a hard, though light, exoskeleton. They possess sharp claws on the ends of their fingers which are used to cut open prey, and as such can easily cut human skin.
  • Large Breasts: As Arachne generally have large bodies, they follow the general liminal rule of having well-endowed breasts too, which don't hinder their movement.
  • Lungs: Arachne have two sets of lungs; a set of lungs in their human torso that are like a human's (inflates and deflates to draw oxygen into the blood cells, as well as separate carbon dioxide), and a set of lungs in their spider abdomen called "Book Lungs", that all arachnids have, that absorb oxygen into the body from the environment without the Arachne needing to "breath" in or out.
  • Pedipalp limbs: While typical spiders use their pedipalp limbs (the two front-most limbs) to assist in eating like typical human hands, the Arachne's do not reach their mouth, plus they have actual hands for holding food. So it is believed that the primary purpose of the pedipalps is to hold their mate in place during intercourse as, due to the Arachne's vagina being located between their pedipalp legs, the legs could easily assist in vaginal penetration. Rachnera shows off how effectively her kind's pedipalps can hold a man in chapter 15 when she restrains Kimihito like this to avoid the beam of a policeman's flashlight (and with some amusement she quickly notices when Kimihito becomes unintentionally aroused).
  • Pattern: Most Arachne are born with an unique pattern on their opisthosoma (spider abdomen). However, Arachne that are members of the same tribe seem to have similar patterns, even with some individual differences, as in the case of Rachnera's tribe.
    • However, as seen in Chapter 53, there also seem to be some Arachne, either individually or depending on the subspecies, who have no pattern.
  • Caffeine intolerance: Like spiders, Arachne can get drunk from ingesting caffeine, as just a single cup of coffee is enough to get Rachnera drunk. In return, however, Arachne are immune to alcohol ( as revealed in Monster Musume: Monster girls on the Job!).
    • However, decaffeinated coffee can be drunk by Arachne without issue, as revealed in Chapter 74.
  • Spinneret: While possessing a primary spinneret at the rear of their opisthosoma (spider abdomen), from which they are able to produce and emit silk like a typical spider, Arachne also possess spinnerets in their wrists which can emit silk in a similar manner. It is unknown whether the different spinnerets can emit different types of silk, at different lengths, thicknesses and strengths, or if they possess the same capabilities and the Arachne simply opts to use whichever spinneret is convenient.
  • Arachne silk: Arachne silk is a rare and valuable commodity. While it has been shown that Arachne can produce and gather enough of their silk themselves to sell, it has been demonstrated that Arachne can also have their silk "milked" directly from their spinneret by machine. The process of having their silk milked out of their spinneret is demonstrably pleasurable and arousing for the Arachne. This supports the notion that an Arachne's rear spinneret is a sensitive erogenous zone that some may enjoy having fingered, touched, manipulated orally, teased and/or penetrated during intercourse.
    • However, not all Arachne subspecies produce silk, such as the Long Leg Breed Arachne.
  • Bondage skills: All Arachne are proficient in bondage, as it has uses in mating and in tying up prey during hunting. It should be noted that Rachnera Arachnera is exceptional at this practice. Tying others up is also noted to be an outright compulsion for their species, as much an outlet for their predatory drives as it is their sex drives, and so depending on context the Arachne may regard a session of bondage in a completely non-sexual way.
  • Temperature Sensitivity: Because of their arthropod nature, Arachne are very sensitive to both high and low temperatures. Higher heat or cold, with which beings like humans or Centaurs would still feel comfortable, would already be too extreme for an Arachne. Because of this, they don't tolerate hot baths or snow very well. It is not known if Arachne are also cold blooded, but they do hibernate and may also die if the ambient temperature is too low.
  • Although they typically wear a loincloth curtain to offer modesty and bikini styles do exist to offer effective "coverage", Arachne do not effectively wear underwear to cover their genitalia (although they do wear bras to secure their breasts). Whether this is a cultural aesthetic or a personal choice is unclear.
  • Diet: As their silk is mainly composed of protein, Arachne require a protein-rich diet to maintain their silk production. Whether a protein-rich diet is also necessary for non-silk producing Arachne subspecies is not known, but Long Leg Breed Arachne prefer to hunt household pests, most of which are protein-rich insects.
  • An Arachne's second abdomen is large and strong enough to hold substantial weight, but doing so appears to be rather uncomfortable for the Arachne (as shown in the anime when Papi and Suu nap together on Rachnera's second abdomen), so riding on them has not been seen.


Small Breeds[]

RaceCardSmallBreed Arachne

The Small Breeds (小型種, Kogata-shu) subspecies is smaller in size than the standard Arachne. Their legs are short, but they can move much faster than standard Arachne, and they are good at jumping and full of energy.

Instead of spinning webs, these Arachne wander around on the ground and leap all over in search of prey. They can produce thread, but they only use it to make safety lines to stop their descent in case they fall or misjudge a jump.

Long Leg Breeds[]

MonMusu Long Leg

The Long Leg Breeds (アシダカ種, Ashidaka-shu) are a large subspecies with thinner and longer legs than standard Arachne. These large Arachne are mild-mannered. They cannot produce thread, but they move surprisingly quickly to secure their prey. Their hunting instincts are so powerful that they will sometimes abandon the prey they have captured to pursue new prey.

As they are especially uncompromising regarding the extermination of household pests, they are respectfully known among those troubled by such pests as “sergeants”.

Large Breeds[]

MonMusu Large Arachne

The Large Breeds (大型種, Ōgata-shu) subspecies is far more heavily built than standard Arachne, with thick legs and a covering of hair. They are very wild and aggressive. In addition to being strong, they also have venom, making them extremely dangerous to approach without caution. That being said however, said venom is not particularly strong nor harmful.

They are not well-suited to interspecies exchange programs, as when they have interacted with humans, they were arrested for assaulting them and causing other problems.


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Main article: Yokai

Jorōgumo (絡新婦 lit. "binding bride"?) are a demi-human species of "spider-woman" originating from Japanese mythology. According to folklore, the species are said to be spiders that can change their appearances into that of beautiful women due to gaining magical powers after turning 400 years old.

Depicted as being skilled at entrapping their prey, Jorōgumo possess many of the same traits as an Arachne; such as possessing six eyes, a light exoskeleton and the ability to produced webs, however, while an Arachne has the upper body of a human and the full lower body of a spider, a Jorōgumo possesses a fully humanoid body with a spider abdomen extending from the base of their spine but no spider prosoma. Also, in addition to their humanoid arms being covered in an exoskeleton, they have six fully dexterous "spider legs" attached to their upper back which they can hide beneath their clothing should they choose.


In the Manga[]

In the Game[]



  • The Long Legs subspecies is the only Arachne who uses katakana for their subspecies name.
  • Arachne weave a durable cloth from their own threads, the main component of which is protein. Its beauty and rarity command a high price on the open market due to its strength, but its true purpose is to merely catch and prevent anyone ensnared in it from breaking free.
    • However the longleg and small breed subspecies don't as the former isn't able to produce thread and the latter only uses her thread to make safety lines.
  • Since spiders are related to scorpions, it can be assumed that Arachne are also related to Serkets and Scorpions.
  • Because of their superior abilities, Arachnes are one of the most powerful and dangerous extra-species in the world.
  • One of the Eight Brothers is dating an Arachne. She is concerned about accidentally hurting her boyfriend during sex due to her claws and at one point calls herself a monster that he should stay away from because of this.
  • The Long Legs subspecies' appearance and nickname of “Sergeant” is a reference to 2chan, which refer to huntsman spiders as “Sergeant Ashidaka” due to a particular thread discussing “anti-cockroach forces”.
  • It is unknown whether Arachne are protostomes or deuterostomes.
  • The appearance and behaviour of the Large Breed Arachne may be based on the Orange Baboon Tarantula. The prominent buttocks in the image may also be reference to the Baboon monkey on which the spider is named after. They're also said to be the only one to possess venom which is different from real-life spiders as all species of them do.
  • The long leg breed subspecies is probably based on wandering spiders.
  • The small breed subspecies is probably based on jumping spiders.
  • Although the species of the Arachne debuted in Volume 3, more details about their culture were only revealed in Volume 16, including the fact that they, like the Lamia and Harpies are a purely female species.
    • With regard to the subspecies of the Large Breed Arachne, this can prove problematic as they are not well-suited to the interspecies exchange program, but they need human males for their reproduction and thus the preservation of their species.
  • In Monster Musume I ♥ Monster Girls Volume 1 Rachnera claims emphatically that despite their spider-like biology, Arachne don' t eat insects. However, this statement could be at least partially wrong, as Long Leg Breed Arachne are known to exterminate household pests, most of which are insects. It is possibly that only standard Arachne don't eat insects, but at least some of their subspecies do, especially since the rather semi-canoical nature of the Anthology calls Rachnera's claim into question anyway.
    • With regard to the Large Breed Arachne, due to their aggressiveness, this could mean that they also eat insectoid Liminal species such as Honey Bees, especially since they are known for attacking humans (which could possibly be one of the other problems that Large Breed Arachne caused.)
    • Small Breed Arachne have been mentioned to hunt prey and that might include insects.
  • Despite having a similar body structure as Centaurs, the reproductive organs of Arachnes are on their human half in the same manner as Lamias and Mermaids.
  • In Monster Musume: Monster Girls on the Job!, it is revealed in Chapter 1, that Arachne are immune to alcohol despite their caffeine susceptibility. Scientific experiments with nematodes (Caenorhabditis elegans), which are not genetically dissimilar to humans, showed that apparently only a single gene (slo-1) determines the effect of alcohol in the body. If this gene was removed from the nematodes, they were immune to alcohol, although it would normally be fatal to the animals. The fact that Arachne are immune to alcohol could indicate that they don't have the gene slo-1.
  • As shown by most members of Rachnera's tribe, the majority of standard Arachne wear loincloths that kept their butts naked.
  • The lower bodies of standard Arachne are probably modelled after the black widow spider and like their real-life counterparts, they prefer dark dwellings. Furthermore, it's unknown whether their subspecies have a similar lifestyle or culture as them.
  • So far, Jorogumo are the only known Arachne subspecies who don't have the lower body of a spider. They are also the only known Arachne subspecies to have only six spider legs instead of eight, as seen in Kuruwa and Komachi, possibly because their two human-like legs essentially take over the role of the two remaining spider legs.

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