Alice Fuji does not have a fun life. She's spent the last few years being tormented and abused by her drunken uncle, whilst her unusual mental disorder and dearth of social skills have led to poor grades and a complete lack of friends at school. Then a mysterious assassin kills her uncle, press-gangs her as his apprentice, and subjects her to TrainingFromHell for a few weeks before trying to kill her when her recruitment application falls through. Now she's got an ever-increasing price on her head as she fends off one murderous, arthropod-themed lunatic after another, and the only allies she can turn to are the slightly ''less'' murderous arthropod-themed lunatics.

A manga written by Shinya Murata since 2009, ''Arachnid'' provides an unusual take on the standard shonen FightingSeries, with an interestingly deranged cast and a wide variety of exotic fighting styles. It also has a spinoff story named ''Caterpillar'', which focuses on an assassin named Imomushi who has her own troubles within the Organization some time before Alice became involved.

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!!'''Arachnid contains examples of:'''

* AcademyOfAdventure: A polite way to describe Alice's school. A less polite (though somewhat more accurate) description would be 'death-trap crawling with murderous psychos'.
* ActionGirl: Alice and virtually any other female assassin.
* AerithAndBob: Most of the characters have insect codenames rather than actual names, while normally-named Alice refuses to give up her identity to the Organization.
* AnimalMotifs: ...or rather, an insect motif, each for every assassin. Alice, however, gets a handful of different spider species motifs for the [[NewPowersAsThePlotDemands sake]] [[CrazyPrepared of versatility]].
* AlmightyJanitor: [[CleanupCrew Undertaker Beetle]] seems to be one.
* AssholeVictim: Alice's uncle in the very first chapter.
* AttemptedRape: Alice from her uncle in the very first chapter, and then Oki from Hibiki's thugs in Chapter 12. Gets worse later, when the main villain brainwashes students into raping any others they can find.
* {{Badass}}:
** BadassCreed: Alice's "kill before being killed" motto.
** LittleMissBadass: Alice, Oki, Kabuto, Geji and Dinoponera.
** TookALevelInBadass: Alice every now and then.
* BewareMyStingerTail: [[spoiler:Sasori]] turns out to have a long cybernetic [[spoiler:scorpion]] tail attached to her back. [[{{Hammerspace}} How was she even hiding that, anyway?]]
* BigBad: [[spoiler:"Army Ant" Sara Kurokawa]] claims she's the boss of the Organization.
* BladeBelowTheShoulder: Dinoponera has extendable needles inside her gauntlets, which have the immensely painful effect of her namesake's sting. Bullet Ant and Suzume Bachi also use this weapon type.
* BladeOnAStick: Kabuto Beetle wields a halberd with enough strength to shove people far away and make craters on the ground.
* BladeRun: Dinoponera sits on Kabuto Beetle's halberd when Kabuto first tries to attack her, then hangs on it to avoid being smashed into the ceiling. Later she also walks on the halberd's pole, too.
* BlandNameProduct: [[Franchise/KamenRider Kahen Rider]]. i.e., Transforming Rider instead of Masked Rider. Later on, [[Franchise/SailorMoon "Sailor-Force"]] is shown.
* BluntYes: Hibiki when Alice asks if he had a [[HoYay "deep relationship"]] with Kumo. Oki then bluntly asks if he is gay. [[VerbalBackspace He confirms it but then he backpedals.]]
* BottomlessMagazines: There's no concern in-story about whether there is a limit on the thread from Alice's Kumoito.
* BrainwashedAndCrazy: At one point Oki is controlled by Digger Wasp, who gives her a dominatrix outfit and has her believe he is Alice. Oki doesn't seem to notice [[NotHimself how unusual]] "Alice"'s orders (such as torturing her friend Yori) are and gladly follows them while not actually being any crazier than she already is. Meanwhile, Sara leads and spreads zombie-like mindless students around for them to overpower and rape her enemies.
* TheBrute: "Sand Cricket" Riokku.
* TheBully: Yoriko is terribly cruel to Alice in the early chapters, to the point Alice considers killing her, but after the first encounter with Sasori, Yori has to keep Alice with her for protection and the two begin to get along.
* CarnivalOfKillers: Alice has a price on her head which increases as the assassins after her kill each other.
* CatchPhrase: When her life's in danger, Alice says she can only kill to survive.
* CharacterizationMarchesOn: When Dinoponera is first seen wandering around Alice's school, she looks [[EmotionlessGirl rather quiet and serious]], but then her stoic look from the [[http://www.iibq.com/comic/82012133790/viewcomic216801/?p=36&s=1 last panel of chapter 35]] became a smug grin on the Volume 7 release and suddenly she's all smiles.
* CharlesAtlasSuperpower: Everybody in this series is a "perfectly ordinary" human. You may need to remind yourself of this repeatedly.
* ChekhovsGun: Oki is able to secrete oil as an evasion ability. Much later Kabuto explains she taught her to subtly do it when in trouble to leave a trail behind her for Kabuto to follow.
* CheshireCatGrin: "Scorpion" Sasori.
* ChildSoldier: Some characters are shown to have been trained by the Organization since they were small. Among them, Dinoponera was the [[ImprobableAge toddler]] doing mercenary work in war zones.
* CrazyPrepared: Alice, courtesy of her DisabilitySuperpower which is very befitting for a spider-themed string user.
** Kabuto Beetle can survive even seemingly lethal stabbings to the heart thanks to her implanted exoskeleton armor.
** Bullet Ant gives Imomushi a lot of trouble, being an experienced mercenary.
** Dinoponera[[spoiler:'s "Concentration Driving Free" ability gives her heightened senses comparable to Alice's]].
* CreepyCentipedes: "Caterpillar" Imomushi and "House Centipede" Geji.
* CreepyCockroach: Oki is creepy in a perverted kind of way.
* CuteAndPsycho: Most of the girls in the series.
* CuteBruiser: Oki, Kabuto Beetle, Geji and Dinoponera. Alice has her moments, but she mostly uses [[RazorFloss string tricks]] to fight.
* DamselInDistress: Early on, Oki fakes kidnapping Yoriko to bait Alice. But later Yori is captured by the Sand and Digger Wasps to be tortured by a brainwashed Oki. She tries to stay out of Alice's fight against Dinoponera, but Dinoponera jumps behind her anyway to get a reaction from Alice. [[spoiler:When Alice reunites with her later, Yori is attacked by Sasori.]]
* DarkSkinnedBlond: Riokku and Dinoponera.
* DeathSeeker: [[spoiler:Kumo trains Alice so she could kill him.]]
* DefeatEqualsFriendship: Oki is brought along by Alice after being defeated. It helps that Oki turned out to not have kidnapped Yori and just wanted [[PsychoLesbian to make Alice her slave instead of killing her]].
* DeerInTheHeadlights: Alice is shocked when Kumo tries to kill her at the beginning, but then she jumps to chomp his neck off. She later becomes feared for being able to avoid being completely frozen even in such dire situations.
* [[spoiler: DecoyProtagonist: You know that cool looking assassin that keeps Alice in his house? Alice kills him at the end of the first volume.]]
* DisabilitySuperpower: Alice's "Congenital Excessive Concentration", which causes her to single-mindedly concentrate on the most inconvenient things. With training, though, it allows her to enter a kind of HyperAwareness state and formulate battle strategies in seconds, and serves as arguably her greatest weapon.
* TheDragon: Suzume Bachi to [[spoiler:Sara]].
* DynamicEntry: Hibiki is fond of arriving from out of nowhere [[ConvenientlyTimedAttackFromBehind with a Rider Kick]]. He gets on the receiving end of it once, courtesy of Oki.
* EnfantTerrible: Digger Wasp.
* ExoticEyeDesigns: Alice's pupils and [[spoiler:Dinoponera's irises]] ripple when they concentrate. Sometimes they get both effects at once when they're [[DeathGlare angry enough]].
* EyepatchOfPower: Sara wears one. Alice wore one while recovering from the battle with Hibiki, but then she looked cute rather than powerful.
* EyesAlwaysShut: Kamakiri acts like this before attacking Alice.
* TheFaceless: Alice's mother during flashbacks, [[spoiler:until chapter 48]].
* FlashStep: The faster characters frequently [[OffscreenTeleportation appear out of nowhere]] [[NoIAmBehindYou behind each other]]. [[BadassBack And they usually look away from the target,]] [[RuleOfCool just to look cool.]] It's later exaggerated in chapter 48, in which [[spoiler:Alice practically teleports around Dinoponera, who insists in trying to hit Alice from behind]].
* ForeheadOfDoom: Yoriko.
* GoombaStomp: Dinoponera at one point almost impales Hikibi's head, but is distracted when she notices Alice is on the floor above her and just stomps Hibiki instead.
* GratuitousForeignLanguage: Dinoponera sometimes speaks in tailandese.
* HairAntennae: Oki, as part of her cockroach theme. They even move while she's detecting movements around her.
* {{Hammerspace}}: Kabuto Beetle hides her Kabuto Horn halberd folded in half under her shirt, but it's still far too big for it to make much sense. Then there's Geji who hits Oki with a heavy filled sock that she was still wearing on the previous page.
* HappinessInSlavery: Oki, after her HeelFaceTurn. It helps that Alice isn't remotely interested in having a slave, and just treats her as a friend instead.
* HardWorkHardlyWorks: Having fought alone in wars during her whole life, Dinoponera expected to find a kindred spirit in Alice, but becomes enraged upon finding out she only recently became an assassin and yet mastered her ability in a couple of weeks.
* HeelFaceTurn: 'Cockroach' Oki, the PsychoLesbian assassin, would be the most obvious example (and overlaps somewhat with HighHeelFaceTurn), though Yori, the AlphaBitch who befriends Alice after the latter saves her life, serves as a less extreme case.
* HoistByHisOwnPetard: How Alice has killed some of the assassins thus far; [[spoiler: Kamakiri (Praying Mantis) slits his throat with his scythes, Amenbo (Water Strider) is held underwater and drowned.]]
** [[spoiler:Water Strider]] [[BalloonBelly held long enough underwater]] for help to arrive.
** Despite her best efforts to defeat Alice, [[spoiler:Dinoponera]] still gets tangled up and forced to stab her own leg.
* HyperAwareness: Alice, Oki, Sasori and Dinoponera have their own ways of feeling the environment around them and instantly countering any threats.
* IJustWantToHaveFriends: Alice has been lonely and shunned by people, Oki doesn't seem completely ok with being alone and hated, and Dinoponera, who also grew alone, would like to meet someone she can symphatize with (she's too picky, though).
* IKnowMortalKombat: Hibiki based his fighting style on the [[Franchise/KamenRider "Kahen Rider"]] series, training until he made reliable techniques out of the show's ideas.
* IdiosyncraticEpisodeNaming: Chapters are named after dialogue or monologues [[TitleDrop said in them.]]
* ImpaledWithExtremePrejudice: Dinoponera repeatedly impales people not necessarily to kill, but to have fun watching them scream because of her stings' [[ToThePain "24 to 48 hours of great pain"]] venom. [[spoiler:Alice gets stabbed all over her arms, legs and butt because Dinoponera was that much pissed off at the time.]]
* [[ImplacableMan Implacable Woman]]: "Giant Needle Ant" Dinoponera steamrolls everyone on her way to meet Alice, [[NoSell unharmed by anything she couldn't block or dodge.]]
* ImprobableWeaponUser: If an Organization assassin uses a weapon, it'll be an extremely weird one. Alice's WeaponOfChoice, for instance, is the "Kumoito", or "Spider's Thread", a length of spider-silk with a hooked blade on the end that works rather like a cross between RazorFloss and a GrapplingHookPistol.
* ImOkay: Only five "insects" are dead by the 40th chapter, a few of the recurring characters even say so after getting back up from the ground. Even [[spoiler:Kumo]] is implied to have faked his death.
* InadvertentEntranceCue: One scene has Imomushi stating she didn't necessarily come to Alice's school to fight her but is interested on the reward on her head. Cue awkward silence as Alice enters the room.
* InsectQueen: Sara, who is Army Ant-themed, can dominate weak-willed people and is followed around by brainwashed minions. [[spoiler:Turns out she's tasked with guiding them, but isn't the one doing the brainwashing...]]
* {{Irony}}: The two times Oki ordered an opponent to be her slave, she became enslaved instead.
* ItsPersonal: Hibiki hates Alice because she [[spoiler:killed Kumo. He doesn't realize Kumo forced her to do that.]]
* ItRunsOnNonsensoleum: Other than Kabuto and her implanted armor, most of the characters don't seem enhanced. But even when their tricks are just plain supernatural, they're able to do them because they somehow fit in their insect motif, without any further explanations other than [[HandWave "they did special training"]].
* JusticeWillPrevail: Having watched a little too much tokusatsu shows, Hibiki claims to fight for justice and love, and regards his opponents as evil.
* {{Kiai}}: Hibiki repeatedly shouts [[ThePowerOfLove "LOVE"]] [[http://mangafox.me/manga/arachnid/v05/c024/31.html while stomping people]] and Dinoponera [[EvilLaugh laughs madly]] when pummeling faces.
* KillingIntent: When in danger, Alice puts all her focus on how she can kill or at least terrify her enemies. Only Suzume Bachi [[KnowWhenToFoldEm gets her afraid enough to flee once.]]
* KnightTemplarParent: Alice's father is implied to be one.
* LanternJawOfJustice: "House Cricket" Hibiki and "Sand Cricket" Riokku.
* LetsSplitUpGang: When a bunch of assassins invade Alice's school to kill her, all she wants is to get her friends out of there, but they keep getting separated for a reason or another.
* LimitedWardrobe: Alice pretty much stays in her school outfit.
* MadScientist: Sand Wasp.
* MakeMeWannaShout: While bored from fighting Hibiki, Dinoponera suddenly stuns everyone in the corridor with a loud scream. [[spoiler:She does it again later to escape after being defeated by Alice, though Kabutomushi isn't affected and almost crushes her.]]
* MaleGaze: Lots.
* ManlyGay: Hibiki.
* MartialPacifist: Despite her killing instinct, Alice would rather not kill people and fights only to protect herself and the few friends she has.
* MercyKill: [[spoiler:Alice does this to Kumo.]]
** Caterpillar to one of Bullet Ant's victims.
* MissingMom: Alice's mother, who was DrivenToSuicide after too much stress. Dinoponera's mother died from gunshot wounds while protecting her. [[spoiler:And the assassins who served as father figures for them are both dead.]] Yoriko's mother died by childbirth and her father is always away. Oki is shown to have grown in an orphanage.
* NearDeathExperience: This trope tends to trigger the killer in Alice, while Dinoponera is shown on a flashback [[spoiler:awakening her own concentration technique]] to survive an ambush, at [[ChildSoldier a very young age]].
* NoSell: Dinoponera seems immune to blunt damage. She gets blown away by a kick to the face and then just stands up with [[SmugSmiler a smirk]]. After this she gets stomped countless times and just gets a bit embarrassed, without damage even to her clothes.
* NotWhatItLooksLike: After Oki defeats Geji, she undresses her to take her clothes, since Oki had [[ItMakesSenseInContext been dressed on a dominatrix getup by Digger Wasp.]] Alice, who didn't know anything, finds her doing this and is disturbed.
* PeoplePuppets: Alice can trap people with her threads to force them to move against their will. And if she happens to be paralysed, she can pull herself around too. She calls it [[GratuitousItalian "Marionette del Ragno"]] in chapter 49.
* PosthumousCharacter: [[spoiler:Kumo's commmentary on some characters' abilities is remembered by those who knew him.]]
* {{Prequel}}: "Caterpillar" Imomushi's storyline.
* ProfessionalKiller: The insect-themed assassins.
* SailorFuku: Dinoponera likely wears one to look like a [[Franchise/SailorMoon Sailor Scout]]. The other girls don't anymore.
* ScaryScorpions: Sasori revels in [[TheParalyzer paralyzing and torturing]] people to death with her poisons.
* ShadowArchetype: From her looks to personality, backstory and abilities, Dinoponera is pretty much Alice with a more physical fighting style and whose lonely background made her [[{{Jerkass}} mean and deranged]].
* SkywardScream: Alice after [[spoiler: she kills Kumo]].
* SmugSmiler: A frequent expression on female antagonists such as Sasori, Geji and Dinoponera.
* SmugSuper: Practically every insect assassin is so incredibly smug about thier abilities that the otherwise humble Alice can't help but join in to counter them.
* SpidersAreScary: Alice normally is [[BewareTheNiceOnes a gentle and kind girl]], but in battle she becomes much colder and creepier.
* StrongAnts: Sara (Army Ant) and Dinoponera (Giant Needle Ant and Dinoponera) are ant-themed. The first seems helpless in battle and depends on her minions. The later is shown to be greatly strong and resistent.
* SuperDrowningSkills: Alice can't swim.
* TheSyndicate: "The Organization", which has much control over the world while remaining untraceable.
* TheseHandsHaveKilled: Alice may be determined to kill when necessary but isn't proud of that.
* TooPowerfulToLive: The excuse [[spoiler:Kumo]] uses to fight Alice to the death.
* TheUglyGuysHotDaughter: Dinoponera to Bullet Ant, but she's adopted.
* UnPerson: The Organization owns all records of their members' existances and is able to erase those if they die. Alice refuses to join them to avoid becoming this.
* UseYourHead: Imomushi's main attack is to catapult herself head-first on enemies.
* WebcomicTime: About thirty chapters all happened in one afternoon. ''Still'' going.
* TheWorfEffect: Oki claims she's the fastest among the assassins, yet gets easily beaten when someone turns out to be more danguerous than her. Kabuto Beetle is shown to be one of the strongest insects around before Dinoponera beats her up. Dinoponera is unmatched for a while until Alice surpasses her, causing Dinoponera to flee [[spoiler:and be cornered and defeated by Sasori as well]].
* {{Yandere}}: PlayedForLaughs when, after befriending Alice, Oki tells her she would kill any boys Alice liked.
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