[[quoteright:250:http://static.tvtropes.org/pmwiki/pub/images/ika-musume_3029.jpg]]

The Lemon Beach House, run by the Aizawa sisters, is booming with customers in the middle of the summer. This peace will be short-lived. A girl calling herself "Ika Musume" (Squid Girl) emerges from the sea, stating her goal of taking over the world as a revenge on humanity for polluting the oceans. This army of one has a long way to go, though. When she breaks a large hole in the beach house, the sisters force Ika to work for them until she can pay for the repairs. Thus begins a cute comedy about the friends at the Lemon Beach House and world domination... supposedly.

Based on Masahiro Anbe's manga, ''Shinryaku! Ika Musume -The invader comes from the bottom of the sea!-'' was adapted into a {{twelve episode anime}} in fall 2010. It's currently licensed and dubbed by Creator/MediaBlasters.

Season 2, titled ''Shinryaku!? Ika Musume'', aired in fall 2011.

Both seasons can be watched legally on [[http://www.crunchyroll.com/squid-girl Crunchyroll]] (subbed), and the first season is also on Netflix (dub).
----
!!''Ika Musume'' contains examples of:

* ACupAngst: When Ika Musume had 3D glasses on and wanted "to feel something that's supposed to be there, but isn't" on her friend Kiyomi. She wasn't too happy about the words, but acknowledged that she only started "growing up" in that area. This led to Kiyomi wishing that her breasts were bigger in one episode
** Nagisa displays some of this when she starts crossdressing and Chizuru suggests they wrap her chest "just in case".
* ADateWithRosiePalms: Chizuru asked Goro not to use the photos he got of her for "bad things". He also was thrilled when Ika Musume wanted to take "embarrassing" photos of Chizuru (Goro of course [[LampshadedDoubleEntendre misunderstood it in a certain way]]).
* AbhorrentAdmirer: Though it isn't in regards to Sanae's looks, but her behaviour.
* AccidentalHero: Instead of making an anti-alien ray gun, the alien researchers found the cure for cancer.
* AchillesPowerCord: The Squid Girl Robot almost catches the real Squid Girl if it hadn't been for it's power cord stopping it.
* AdaptationExpansion: Typical manga chapters of Ika-Musume are only 8 pages long, so this tends to happen in the anime in addition to the ThreeShorts format.
** In the manga version of "Won't You Study?", Ika gives Eiko her "simplified" calculation method immediately after Eiko begs for it and the chapter ends shortly after. The anime adds in a scene where Ika is running Eiko ragged in the restaurant and trying to show off her math skills.
** Special mention goes to the SickEpisode (Episode 8-1 and Chapter 103), which not only blended another SickEpisode, chapter 70, into the anime version, but turned the manga's ending into an entire episode, namely 8-2.
** In chapter 49, "Won't you lose weight?", it's discovered that Ika actually weighs quite a bit more than she appears. Eiko forms a few theories as to how, but the actual reason remains a mystery. When this got adapted in episode 2-3 of the second season, the question was answered: Ika's bracelets are devices that allow her to freely manipulate her body weight, usually increasing it to counterbalance herself when she lifts heavy objects with her tentacles. However, she can also decrease her weight to the point that she can ''fly'' by spreading her tentacles like wings.
* AlertnessBlink: In the opening and episodes alike.
* AllJustADream:
** [[spoiler: The "Won't You Keep It?" segment was Sanae's dream.]]
** [[spoiler: And in S2 E6, Mini-Ika's adventure is all Goro's dream.]]
* AllPartOfTheShow: during the Nohmen Rider stageshow, [[spoiler:Chizuru]] is disguised as Nohmen Rider Hannya, allowing her to bust out her CrazyAwesome moves in full view of the public. [[spoiler:Which happens again in ep. 12.]]
* AlwaysABiggerFish: invoked in ep. 11 when Ika and the family hike up a mountain, encountering animals that keep getting scared off by bigger or more dangerous animals, culminating in a king cobra. [[spoiler:Amazingly, it doesn't bite Ika - ''it [[CurbStompBattle curbstomps]] her''.]]
* AmazinglyEmbarrassingParents: Goro's mother shows up in OVA 2.2, and causes a lot of headaches for him, such as telling him not to just watch girls on his lifeguard duty and teasing him about Chizuru. However, she later tells him that she's been secretly watching him do his duty and is proud of his work too.
* AmplifiedAnimalAptitude: Alex, Sanae's dog, seems to understand human speech quite well.
* AndThenWhat: Brought up in Episode 5.2 of Season 1, and again in Episode 12.1 of Season 2.
* AnimeAccentAbsence:
** Despite their own fluency, the three scientist colleagues avert this trope -- the voice actors try to give their characters stereotypical "American" accents.
** {{Lampshaded}} and {{inverted}} in [[http://www.mangapark.com/manga/SHINRYAKU-IKA-MUSUME/c119/5 Vol. 7]], where Ika Musume questions Cindy's English abilities. Cindy tries to defend herself, but is horrified to realize that her English has developed a Japanese accent.
** Also slightly justified, as the inventors off-handedly explain that they've created a device that [[ReedRichardsIsUseless taught them all languages, (as well as invent the cure for cancer.)]] They openly admit that they only care about the romantic ideal of alien prevention.
* ApathyKilledTheCat: Eiko is the one who most actively challenges Ika, but she's more concerned about getting work done. Takeru considers her a playmate. Chizuru cares about ''her'' getting work done. The fact that she's a talking squid girl is of no importance. Nagisa is the only one that seems to care that Ika's something not seen in this world.
** Averted with Cindy and friends as they actively try and learn more about Ika.
* ArrowCatch: Sanae, of all people, nullifies an arrow trap aiming for her head in season 2's episode 6 part II. Lampshaded by the fact it was her who set the trap in the first place. But still, catching an arrow barehanded with two fingers is [[BadassNormal pretty impressive for a normal human girl.]]
* ArtShift:
** There's a very brief one in episode 3 when everybody sans Chizuru is running away from Ika.
** Episode 10 includes plenty of these, especially when Ika Musume draws. Takeru gets one [[spoiler: when he sees the "mother of all teru-teru-bouzu"]] as well.
** Also parodied: Takeru draws Ika Musume ''exactly as she appears on screen'', then complains that it looks too much like a cartoon.
** Eiko has a slight ArtShift whenever Chizuru forces something covered in Ika's ink on her and she finds it to not just be edible, but actually REALLY GOOD.
** Ika Musume, whenever there's a full-screen portrait of her being [[http://media3.giphy.com/media/fExqAqMsIZ4Q/200_s.gif scared shitless by Chizuru.]]
** The Southern Winds Owner's face could be considered an ArtShift, it's drawn in a completely different style than everyone else's face in both the manga and anime.
* AscendedMeme: "You gotta be squidding me!" actually made it into the dub.
* AttackAttackRetreatRetreat: In the RPG game Eiko and Squid Girl play in OVA 1.1, they are seen rushing into battle in one scene. In the very next scene, they're both running away from giant monsters chasing after them.
* AttractiveBentGender:
** Takeru after putting on makeup in episode 9.
** Also Nagisa when she dresses up as a boy, leaving a huge impression on the female customers.
* BadassAdorable: Ika-Musume when she actually tries, and Chizuru ''as natural as breathing air.''
** Which is suspicious enough to Cindy and her team that they try to get a lock of Chizuru's hair for analysis.
* BadassArmFold: Ika sports one of these in episode 1, complete with manic grin and red-and-black cool-looking background.
* BalloonBelly:
** Ika-Musume gets this when she gorges on food (usually [[TrademarkFavoriteFood shrimp]]).
** Eiko gets this in the manga after gulping down the contents of a cart of drinks.
** Both of them, after gorging on meat in Episode 2.10.1.
* BaseballEpisode: Episode 10.3, where Ika joins Kiyomi's baseball team.
* BattleAura: For [[SeriousBusiness building sand castles.]]
* BeamOWar: Done in Season 2's Episode 11: Ika Musume faces off against a machine meant to replace her and the fight devolves into a ink spitting battle.
* BewareTheNiceOnes: Do not mess with Chizuru, her family, or her store. She will hurt you. [[spoiler: It wasn't until the scientists turned the store invisible by accident that everyone else realized what Ika feels from Chizuru on a daily basis.]]
* {{Bifauxnen}}: In chapter 148/Episode 2 of season 2, Eiko makes Nagisa dress up as a guy to attract more female customers.
* BirthdayEpisode: In one episode, Squid Girl discovers the surface dwellers' custom of birthday parties, and declares today to be her birthday to take advantage of the goodies.
* BishieSparkle: Chizuru turns up the sparkles to convince Goro to watch Takeru for her. It works.
* BigEater
** Squid Girl. She appears to be capable of eating an endless amount of shrimp. As in, $100 worth in one sitting. Mini-Ika takes it UpToEleven.
** Goro's mom in OVA #2.
* BlandNameProduct:
** In episode 9 Ika and Kiyomi play ''[[StreetFighter Stocking Fighter IV]]'' and Ika picks Dhalsim-expy Mr. Yoga.
** And then they get a copy of ''[[SonicAndSegaAllStarsRacing Hedgehog Kart]]''.
** [[Creator/{{Nintendo}} "Mintendo"]] in the Season 2 OVA.
* BlatantLies: When Ika gets amnesia in episode 7.2 in Season 2, Cindy and Sanae concoct a made up story of how she's an alien (Cindy) and fell in love with Sanae at first sight (Sanae). Ika nearly falls for it until Eiko tells them to stop trying to screw up her memory.
** In chapter 110, Chizuru is definitely NOT using her pedometer for a diet... Yeah, right...
* BlueWithShock
* {{Bowdlerise}}: In the manga, when we first see Chizuru get serious and fight Ika, she cuts off Ika's tentacles with a knife. In the anime, she does it with her bare hands. [[TropesAreNotBad However,]], this just makes her look ''even more'' badass.
* BreakingTheFourthWall:
** Cindy narrates the beginning of episode 10's second skit. She's talking to ''someone'' and is staring at the screen most of the time.
** Ayumi is really [[ShrinkingViolet shy]] so she doesn't [[TheQuietOne talk much]], but then there's one panel where she fills it with text.
-->'''Ika''': It's like she is trying to make up for lost time in one panel.
* BroughtDownToNormal: [[spoiler:Ika in episode 12. In the manga version of this story, Ika's abilities are restored when she is "attacked" by an orca float.]]
* BrickJoke: At the end of S1: ep 5.2 Eiko tells Ika she should finish elementary school before going to Eiko's school again. [[ExactWords Guess where she goes in S2: ep 2.1...]]
* BuxomIsBetter: Several male customers refer to Ayumi's assets as [[UnusualEuphemism her having "romance"]].
* CameraFiend: Sanae has entire photobooks of Ika, and more or less holds her hostage to get more. The so-called invader is powerless against this.
* CardCarryingVillain: Ika Musume is not a fan of the "winning the people's hearts" method of world-conquering, and considers being fearsome and terrifying to be job requirements. Nothing depresses her more than people thinking she's nice, and consequently she has a soft spot for Nagisa (who's scared to death of her).
* CatGirl: [[NinjaPirateZombieRobot Cat Squid Girl]], actually. [[http://www.mangapark.com/manga/SHINRYAKU-IKA-MUSUME/c113/4 Behold!]]
--> '''Eiko:''' How odd... (because of the squid portions)
* ChekhovsGun: Ika mourning over an empty squid hat is justified - ''because it's fatal''.
* ChekhovsGunman: Noh Mask Rider Hannya, [[spoiler: Chizuru's disguise, although she fake-reveals herself to be Eiko]], who is introduced once in one of the earlier episodes, but makes a second appearance in the final episode of season one.
** Remember Takeru's teacher, who only appeared in the anime once? [[spoiler:She's Nagisa's older sister.]]
* ChewToy: Ika during the mountain episode, literally. A ridiculous amount of animals come to her because they want to eat her tentacles. HilarityEnsues.
* ColdTurkeysAreEverywhere:
** Sanae attempts to give up on Ika, and the results are not pretty. She starts seeing Ika everywhere she goes...
** Used again when Ika tries to give up shrimp.
* CombatTentacles: Ika's... hair/tentacles/whatever are quite strong and versatile; they're able to punch through concrete, move fast enough to break the sound barrier and extend to ridiculous lengths, yet also precise enough to thread needles. Additionally, just like a normal squid, she's able to regrow them in the event that they're chopped off, albeit much faster.
* ComedicSociopathy: In universe example: When Eiko sends Ika Musume and Nagisa on a shopping trip together she states that she hopes it will help them get along better (make Nagisa see Ika Musume isn't scary) Chizuru says "I thought you sent her along because it's funny".
* ComicBookTime: If [[http://www.mangapark.com/manga/SHINRYAKU-IKA-MUSUME/c183/4 this page]] is any indication, the entire series since Cindy's introduction has taken place during her summer vacation. That's around 200+ chapters, which either speaks poorly of the passage of time or positively of her benefits at work. Subverted in the anime though, where the last episode of the first season makes it clear that Ika Musume was almost a full year away since we see changing seasons. This would lend for about 180 days maximum (two summer seasons) which sounds reasonable for the amount of chapters.
* ComicallyMissingThePoint: In the jellyfish collecting contest designed to clean the ocean of jellyfish, Clark wins by collecting one jellyfish, and ''creating dozens more'' with a duplication ray.
** When Chizuru is watching Sanae swim obscenely fast after Ika's lipstick unlike Eiko and Nagisa, Chizuru decides to comment on Sanae's butterfly stroke.
* CompanionCube: Ika's Umbrella in Episode 8. [[spoiler:She doesn't give it up, however, in the Couch Gag.]]
* CosmeticCatastrophe: A ''tiny'' bit of makeup flatters Ika very nicely, but then she tries to figure out whether makeup can also make her look more menacing...
* CosplayOtakuGirl: Sanae loves putting Ika in all kinds of different costumes.
* CouchGag: What will show up on the beach with Ika in the closing credits ''this'' episode?
* CreepyDoll: The alarm clock doll that Eiko takes out of storage. It sits directly in the UncannyValley and refuses to leave. Even Eiko gives it away at the end, for its broken friend scares her even more.
* CreditsRunningSequence: season 2's ending has Ika walking on the beach (while the first season was static with her watching the ocean), and there will be some event from the episode that makes its appearance in the sequence. The ending of Episode 6 replaces Ika with [[FunSize Mini Ika]].
* CryCute: Ika-chan was weeping for a ''paper hat'' that looked like a dead squid as it flowed out into the ocean... the family just didn't have the heart to tell her that it wasn't a "comrade" of hers.
** Or whenever Chizuru scares her.
* CurbStompBattle: Chizuru vs something. Chizuru ALWAYS WINS.
** In episode 11, Squid Girl takes on a cobra. The cobra takes Squid Girl out in one hit.
* CurtainsMatchTheWindow: Common in the cast, Ika chief among them.
* CutTheJuice: The Squid Girl robot made by Mr Tokita, Harris, Clark and Martin has its power source cut off when Nagisa trips and disconnects the cord. Luckily, they were prepared enough to have an emergency backup through auxiliary power ... by a pedal-powered generator.
* [[CuteMonsterGirl Cute Squid Girl]]: Ika Musume herself. [[spoiler:It's hinted there may be others around with a similar background]].
* CutenessProximity: Eiko around Alex, Sanae's pet dog. Then there's Sanae around Ika, [[LesYay though that soon evolves into something else...]]
* DancePartyEnding: The final credits of Season 2.
* DebutQueue: Each episode in Season 1 introduces a new character or two.
* DeepImmersionGaming: The RPG game Eiko and Squid Girl play in OVA 1.1.
* DidntThinkThisThrough: Eiko asks Squid Girl this in the first episode when the latter stated her intention of invading and taking over the world. She asks the latter how she plans on conquering the entire planet as well as how to deal with all of humanity's armed forces, overwhelming her a bit. So Squid Girl downsizes her plans a little, and decides to just take over the lemon shop first, although she fails at that as well. So she settles for just living on the surface...for now...
** At the volleyball tournament, the scientists show off their newest gadget: an incredibly hard ball, designed to be completely impossible to receive. Which means it's also impossible to serve.
** Ika manages to "conquer" the local high school by tying up the principal. She then commands the students to be her soldiers so she can conquer the world! Unfortunately, the only thing she has planned after she conquers the world is...eating as much shrimp as she likes. Which she already does anyway.
* DoesNotKnowHisOwnStrength: In OVA 1.1, the three stooges create a handheld console that's unbreakable, and it lives up to its name, as they throw it against the wall in the Lemon house shop, only to have it leave a crater in the wall. Unfortunately the buttons are also extremely hard to press as Eiko and Squid Girl discover while struggling to even play the NintendoHard games on there. After a while they give up, then go to play Eiko's regular console, only to have her smash the game cartridge, and Squid Girl breaks the controller, due to having gained a lot of strength from having played the handheld console from earlier.
* DracoInLeatherPants (In-universe example): During a stage play Ika gets the crowd to cheer for the villain (a squid monster) instead of the hero like the makers intend.
* DreamSequence: The [[spoiler: Mini-Ika episodes]] turn out to be these, the first of Sanae, and the second of ''Goro'' of all people.
* DynamicEntry: Flawlessly performed by Eiko to stop Ika's invasion of the school.
** And again by Eiko to stop Isozaki from hitting on Ayumi.
* EasyAmnesia: Ika gets this in Chapter 106 (Season 2, Episode 7.2 in the anime) by falling down the stairs. She gets better at the end of the chapter by trying to remove her hat.
* EpicFail:
** Episode 11. Ika gets her ass kicked ''by a creature without legs''.
** In the first segment of the second episode of the second season, Ika tries to play soccer, but she can't even do the simple act of kicking the ball! In fact, in order to win the game, [[spoiler:her teammates make it look like she kicked the winning goal!]]
* EvenTheGirlsWantHer: Nagisa is a minor case; all she needs to do to attract female customers is ''just sweep her hair back.''
* EvilCounterpart: In one of the DVD shorts, Mini!Ika is attacked by Dark!Mini!Ika, a wandering squid girl who enters into the house through the open window. [[spoiler:It turns out to be inverted. She was just looking for food, and aside from being very competitive, is actually very nice.]]
* EvolvingCredits: After the first episode, the ending credits changed slightly in each episode, featuring something seen in the episode.
* ExactWords: When she sees the preferential treatment Alex is getting for being cute, Ika demands "You will treat me just like this creature!". GilliganCut to Chizuru putting her on a leash.
* ExcitedShowTitle
* {{Expy}}: A large proportion of the ''ToAruMajutsuNoIndex'' fandom have noted Ika-Musume's similarity in appearance and personality to the titular nun Index. [[http://safebooru.org/index.php?page=post&s=view&id=360571 For example.]] This similarity turned into an AscendedMeme with [[http://www.youtube.com/watch?v=VSY69ehDMdE the third episode]] of "To Aru Majutsu no Index-tan" (a DVD extra of ToAruMajutsuNoIndex), where Index got replaced with a chibi version of Ika Musume.
* EyesAlwaysShut: Chizuru. Beware if she opens them.
** It's shown in chapter 76 that she has bad eyesight, so she's always squinting. She gets contact lenses, but gives them up when she realizes that having her eyes open all the time makes everyone else nervous.
** There's also one brief exception in season 1 when Chizuru gets an idea and her eyes open right before the scene cuts away. Though only the viewer sees this.
* FaceYourFears: In Season 2, Episode 11.3, [[spoiler:Ika overcomes her fear of Chizuru, accidentally ticks her off again, and ''gets dragged by her to a room while'' '''''showing NO signs of fear.''''']]
---> '''Ika:''' Oh? About what? [[spoiler:(while being dragged by Chizuru to a room)]]
* TheFaceless: Ayumi is an interesting twist, bordering on double subversion: she's not ''always'' seen in an Ika Musume mask, but she's too shy to truly be herself when her face isn't hidden.
* FalseDichotomy: When Ika gets amnesia, she's told in succession that she's an alien, Sanae's lover, and Eiko's little sister. She decides the first two aren't right, [[http://www.mangapark.com/manga/SHINRYAKU-IKA-MUSUME/c106/5 so by process of elimination...]]
* FanDisservice: Chizuru stripping the three male scientists.
* FanService: Appears to be actively averted. The show takes place on a beach and has a largely female cast, yet none of the main cast are shown in a suggestive way -- just a few side characters in bikinis now and then. It's rather refreshing.
** Ayumi has a full page in vol.6. Fanservice is still rare and not the focus.
** Cindy provides the obligatory ForeignFanservice, of course.
** Season 2 probably uses this trope ''a bit.''
* FeminineWomenCanCook: Subverted with Nagisa, who makes [[http://www.mangapark.com/manga/Shinryaku-Ika-Musume/c97/7 a surprisingly good vegetable soup]]. She ends up trying to hide it, [[http://www.mangapark.com/manga/Shinryaku-Ika-Musume/c97/8 but not because of femininity.]]
* FertileFeet: Or, rather, fertile ink. Ika Musume's ink had accelerated the growth of her melon plant to such a degree that after a week, they covered the whole house of the Aizawa family!
* FeudEpisode: Season 2 Episode 12.2: ''Isn't That A Festival?'' Ika and Eiko have a falling out and the rest of the sequence focuses on their making up. It's also the season finale.
* {{Flanderization}}: While Ika is usually portrayed as intelligent, but easily distracted (because of her curiousity about life on the surface world), season 2 seems to have started making her more ''KeroroGunsou''-like. For instance, in episode 9-2, Ika is blatantly portrayed as CompletelyMissingThePoint of using a bag and planner.
* FlashStep: Chizuru demonstrates this ability when angered by Ika in Season 2 Episode 11.
* FlatEarthAtheist: Squid Girl doesn't believe in ghosts, even though a horde of them helped her find her way out of a graveyard once. Her belief is justified in that she didn't even know what a ghost ''was'' at the start of the episode, so she thought they were just weird-looking humans.
* FollowTheLeader: to ''KeroroGunsou'', down to having Expies of Fuyuki, Natsumi and Aki. And a VerbalTic, de arimasu. Interestingly, ''Keroro'' sometimes features an underwater civilization that could execute a ''far'' more effective invasion if need be.
* FreezeFrameBonus: Season 2 Episode 5 Part 2 - Kiyomi's 'hidden' wish is never said out loud, but the camera briefly shows it to you before she snatches it away and destroys the wish. [[spoiler: [[ACupAngst It's for a bigger bust.]]]]
* FriendToAllChildren: Ika gets along really well with Takeru and the other kids at the beach.
* FunSize: [[http://www.mangapark.com/manga/Shinryaku-Ika-Musume/c38.5/1 Mini Ika Musume]]. TastesLikeDiabetes indeed.
* FunWithForeignLanguages: Season 2, Episode 4.1, particularly the hilarious InMyLanguageThatSoundsLike thing between Cindy and Eiko.
* TheGenericGuy: Takeru. According to Ika, anyway.
* GeniusDitz: Ika Musume is able to use a cellphone and camera without reading the manual or hearing an explanation on what they're for or how they work. She's able to perform high-level math as well without batting an eye, not to mention being able to pick up Japanese (and later English!) in ''minutes''. She's also one hell of a drummer and baseball pitcher too. So far (much to her annoyance), invading is the only thing she really sucks at.
* GenkiGirl: Ika and Sanae.
* GodivaHair: at one panel when Ika took a bath.
* GoshHornet: When Ika hits a sunflower in chapter 141 and a bee stings her nose.
* GratuitousEnglish:
** The alien researchers from America speak broken English.
** In the very first episode of the anime, when Ika Musume is explaining her tentacles' abilities to Eiko:
--> '''Ika Musume:''' ''Speed! Power! Reach! Delicacy!''
** In Season 2 Episode 3.3, when Goro suggests Ika Musume become a lifeguard, the picture demonstrating her tentacles being used includes the word "speedy" as an UnsoundEffect.
** Season 2, Episode 4.1 is basically one ''big'' GratuitousEnglish moment.
** From the OnTheNext section at the end of Episode 6 of Season 2:
--> '''Cindy:''' ''Thank you for watching!''
* GreaterNeedThanMine: Goro. He urged Ika Musume to save a kid that drifted too far off, even though he himself was drowning.
* GreenAesop: Don't pollute the seas or [[SpaceWhaleAesop some squid girl might try to take over the world]].
** BrokenAesop: Pollute the seas so [[{{Moe}} some squid girl will try and take over the world]].
* GretzkyHasTheBall: Ika in Soccer.
* HopelessSuitor: Sanae with regard to Ika.
* HotScientist: Cindy
* HumansAreBastards: Alluded to; when you think about it from ''her'' perspective, Ika Musume's so-called invasion is quite justified when you have to watch your loved ones literally choke by our garbage every day.
** Or the fact that Japan is well known for overfishing their waters. That said the show is more HumansAreFlawed: everyone is good, they just shouldn't dump trash in the water. [[spoiler:Part of Ika's character development as the show goes on is her own realization of this.]]
* HurricaneOfPuns: In the ''ink''lish dub, Ika s''beaks'' almost entirely in puns. If there's e''fin'' the s''mollusk'' chance of her ''kraken'' a "fish" or "squid" pun, she'll do so.
* IdiosyncraticEpisodeNaming: All the episode/chapter titles are in the form of questions, ending with, in Japanese, "-na'''i ka'''", which signifies a question in the informal mode, with the "i ka" in katakana for emphasis. This makes for a pun with "ika", which by itself means squid.
** PunBasedTitle: [[{{Woolseyism}} Since that doesn't work in English]], the translation makes most of the chapter titles' puns on "Squid," "Ink," or "Fish," such as "Feeling Inkquisitive?" and "How about a squiddle walk?!"
* IdiotBall: Cindy carries it for a little while in S2 4.1 when she fails to realize Eiko is still speaking Japanese instead of English and the InMyLanguageThatSoundsLike phrases get more and more ridiculous. It's still hilarious though.
* IJustWantToBeNormal: In OVA 1.2, Ayumi is seen talking to Chizuru and Squid Girl normally, while avoiding Eiko and some of the others. They wonder about it, and Ayumi tells them she can talk to non-humans okay but not regular ones like Eiko. [[WhamLine This hits]] Chizuru rather hard as it implies she's not human. She then spends the rest of the arc trying to act normal, such as how to react to a banana peel on the floor, and whether to slip on it normally, or dodge it with her SuperReflexes. [[spoiler:In the end she allows herself to slip on it, but then overreacts by rolling halfway through the shop, breaking a wooden pillar, and smashing a hole into their wall. Eiko then comments that a normal person would probably have been killed if they did what Chizuru just did.]]
* ImTakingHerHomeWithMe: The beginning of "Won't You Keep It?". Sanae tries to do this on a regular basis to Squid Girl, but always gets punched away.
* [[spoiler:ImportantHaircut]]: [[spoiler: Ika in episode 12. [[FridgeBrilliance Interestingly, she cuts her tentacles at the same angle as Eiko's hair]].]]
* InSeriesNickname: The Three Stooges, for the MIT guys. Even Cindy herself calls them that (''in English!'').
* IneffectualSympatheticVillain: Ika Musume-chan.
* InnocentFanserviceGirl: Averted. Sanae wanted Ika to be this, and was very disappointed to discover that, yes, she does wear something under her dress. And not even panties: she wears a modest one-piece swimsuit so that ''nothing'' is exposed when Sanae gets a peek.
* InsaneTrollLogic: In episode 10.2 of Season 1, Sanae attempts to get rid of her obsession with Ika. Although it's hard, she seems to manage to do it, and starts to act somewhat normal around Ika. Near the end of the episode however, after Ika greets her normally, Sanae reasons that Ika greeting her must mean she really wants her instead. Which then causes her to then attempt to do TheGlomp on Ika, and causing the latter to [[StatusQuoIsGod resume hostilities towards her.]]
* InstantExpert: Squid Girl/Ika is able to do complex math and [[GratuitousEnglish speak English]] with little more than a quick glance at the books. Which annoys Eiko to no end, as it's difficult for her to pick up either subject.
* InsultBackfire: Calling Ika "fearsome" and "dangerous" is exactly what she wants. This makes her attached to Nagisa, which only scares Nagisa more.
* {{Kimodameshi}}: Happens in episode 3.1 of Season 1, complete with GhostLights.
* LastEpisodeNewCharacter
* LaughingMad: Eiko, when she finds out Squid Girl is far, far better at math than her.
* LawyerFriendlyCameo: [[KamenRider Nohmen Rider]]. Ika, of course, roots for the Dr. Shinigami-like squid monster.
* LeaningOnTheFourthWall: In Episode 10 of Season 1, Ika Musume draws each of the characters. When Takeru takes his turn trying to draw Ika Musume, his drawing looks exactly like her, but he complains that his drawing looks sort of like a manga or an anime...
* LightEmUp: Like certain species of squid, Ika's able to make herself luminous.
** LightIsNotGood: and there is the fact of Ika being a VillainProtagonist.
* LoopholeAbuse: In one episode, Ika plays soccer with some of Takeru's schoolmates. However, she doesn't know how to play, and when she's told she can't use her hands, she resorts to using her tentacles instead, which to the kids still looked like she held the ball in her "hands".
* LoveDodecahedron: The "chain of attraction" [[http://i.imgur.com/yzoisQP.jpg observed by Eiko]]: Sanae is obsessed with Ika, who loves terrorizing Nagisa, who has a crush on Goro, who is in love with Chizuru.
** And then Kiyomi and her friends enter the picture, too.
--> '''Eiko:''' I don't even want to imagine the relationship map for this.
* MachiavelliWasWrong: Inverted in that Chizuru is able to keep Ika's world-conquering ambitions down simply by looking at her. It's supposed to be a comedy/slice-of-life series, so it doesn't focus on the fact that Chizuru is controlling Ika through fear alone.
* MadScientist: Cindy's colleagues. Ayumi's father has several MadScientist traits, too. He eventually teams up with them to build the ultimate robotic Ika Musume, as seen in Chapter 181 (Season 2, Episode 11.2 in the anime).
* {{Meganekko}}: Kiyomi Sakura.
** Ika briefly became this in Chapter 215 of the manga, in an effort to [[SmartPeopleWearGlasses make herself smarter]]. [[GogglesDoNothing It didn't work]] but, of course, Sanae loved it.
* TheMenInBlack: In chapter 170 (Season 2, Episode 6.2 in the anime), Sanae becomes Ika's Secret Service. The chapter ends with Sanae beating herself up over it. [[http://www.mangapark.com/manga/Shinryaku-Ika-Musume/c170/8 Literally.]]
* MessageInABottle: Used in OVA 2.3. Squid Girl and Takeru send out these messages, but hers keeps returning for some reason. Eventually Cindy and her three stooges help out by building a rocket, but the rockets either hilariously fail, or in one case, works a [[GoneHorriblyRight little too well]] and sends the message into space. In the end, Eiko asks her why she doesn't just use her tentacles, and Squid Girl does that. [[spoiler:At the end, a giant shrimp is drawn on the beach by an alien, who received the message that was sent into space.]]
* ModernMajorGeneral: Ika seems able to do nearly anything... except the thing that matters most to her: [[TakeOverTheWorld invasion.]] The huge global population, [[spoiler:tentacle-severing karate chops,]] and [[StatusQuoIsGod status quo]] make her invasion [[JustForPun dead in the water.]]
-->'''Ika:''' "[[LampshadeHanging Why do I have to be good at everything]] ''[[LampshadeHanging but]]'' [[LampshadeHanging invading, de geso~?!]]"
* MoodWhiplash: "Won't You Keep It?" runs the gambit from cute, to funny, to sad, and back to funny again.
* MultiArmedMultitasking: Ika appears to specialise in this with her tentacle hair.
* MundaneMadeAwesome: Eiko's speech on how important Korean meat grilling is.
* MundaneObjectAmazement: Being an invader from the sea, this is to be expected. Especially in the last segment in Episode 8.
* MundaneUtility: Ika possesses ten tentacles with super strength, super speed and super dexterity. They come in really handy in her job as a waitress. Oh, and the squid ink she can produce makes a formidable pasta sauce.
* NewAgeRetroHippie: After following her bamboo boat along the river all the way to the sea, Ika ends up at the ''[[Music/TheBeatles Lenon]]'' (sic) Beach House.
* NiceHat:
** Ika has a white hat that resembles a squid's head, but it may be more than that. Episode 6 states that if it is detached from her head, she'll '''''die'''''.
*** It's shown that she really WILL die if it's removed in Chapter 106 (Season 2, Episode 7.2 in the anime) because, for all intents and purposes, it's ''part of her skull''. She tries to forcibly pull the hat off, which works about as well as a human trying to tear off his own scalp. Eventually she creates a small rip, the shock of which was enough to clear away her EasyAmnesia.
*** She wears a more conventional NiceHat ''over'' her squid hat in Episode 3.1 of Season 2 (Chapter 167 in the manga, which also shows the MIT trio wearing ''UFO hats'').
** Also, Goro's lifeguard hat.
* NightmareFace:
** Chizuru, most of the time when she opens her eyes. However, she looks normal, even cute, when she wears contacts as shown in chapter 76.
** Ika Musume's Teru Teru Bouzu come out to this.
* NintendoHard: In-universe example with the games on the handheld console the three stooges develop in OVA 1.1. In one example, Squid Girl picks up a pistol, only to find out it fires over the enemies, with no way to hit them as they're too small. In another example, Eiko jumps to dodge an enemy, only to have it jump towards her, killing her character. Later in the RPG game they play, they fight a flying slime, who shoots a giant beam of death and vaporizes Eiko.
* NoCelebritiesWereHarmed: Harris looks a lot like BarackObama.
* NoDialogueEpisode: Episode five's third short is, except for a short dialogue between Sanae and Eiko, a single line of narration, and a few "geso"s, done entirely without dialogue. [[spoiler:This makes the entire short ten times more effective than it would otherwise be.]]
* NoNameGiven: Ayumi's father.
* NoSocialSkills: Ika is a Squid Girl and grew up in the ocean. The human world is right outside her experience.
--> '''Ika''': "What's a military?"
* {{Nosebleed}}: Sanae frequently gets these when she's around Ika. Whether it's brought on from physical punishment or just being a pervert (it's both), it's often lampshaded by others.
* OddlyVisibleEyebrows
* OhCrap:
** The supposedly sweet big sister Chizuru is good at inducing these moments in people.
** Nagisa on first seeing Squid Girl.
* OjouRinglets: Ika acquires these after one of her makeover sessions.
* OneDialogueTwoConversations: Ika and Goro both consider themselves "protectors of the sea", and thus form an uneven alliance, as their motivations (world domination vs. saving people) are rather different.
* OnlySaneMan: Nagisa considers herself to be this, seeing as she's the only one in the whole beach to consider Ika-chan as actually threatening. Understandable, as she's never seen Chizuru in action (she finally ''does'' at the end of episode 9, and her reaction is what you'd expect). Narratively, though, Eiko fills the role more obviously; she's incredulous about Ika's origins at first, she's often the one who has to rein the other characters in (Ika and Sanae in particular) and her only "quirk" is her [[FieryRedhead hot-ish temper]] (and really, given how Ika acts, can you blame the poor girl?)
* OOCIsSeriousBusiness: When [[EyesAlwaysShut Chizuru]] opens her eyes, expect to get your ass handed to you.
* OurGhostsAreDifferent: They're not trying to spirit you away to the afterlife, they're just showing you a way back home.
* PacManFever: An odd mix. Eiko's game system is a cartridge-based one, with plenty of [[ShoutOut Shout Outs]] to actual 16-bit era games (especially {{Sega}} games,) but it also plays a BlandNameProduct version of [[StreetFighter Street Fighter IV.]]
* PaperThinDisguise:
** Literally. Takeru pretends to be Squid Boy with a disguise consisting of a paper hat and coloured strips of paper. Ika falls for it. [[CrowningMomentOfFunny Even when it's removed.]]
** Chizuru in episode 12 after Eiko crashes into her. She then switches places with her and dons a wig and the Noh Mask Rider Hannya mask -- with her real hair hanging out quite obviously.
* ParentalAbandonment: Chizuru, Eiko and Takeru are siblings and live together, but their parents seem to be nonexistent. So far it has not been mentioned if they are away or dead, but Chizuru says in the fifth volume of the manga that nobody uses their bedroom anymore. They appear in a HappyFlashback Eiko has in Chapter 79 (Season 2, Episode 9.3 in the anime), [[spoiler: which makes her cry]].
* ThePeepingTom: The burglar from Season 2, Episode 8.1 (Chapter 127 in the manga) was captured because Sanae saw him through one of the surveillance cameras she had set up at the Aizawa residence ''without them knowing''.
* PettingZooPeople: Ika herself. Also, the apparent [[spoiler:octopus girl]] Ika meets at the beach.
* PhenotypeStereotype: Cindy.
* {{Pixellation}}: Happens to Ika's tentacles during episode 4.2 of season 2.
* PlayingHouse: Season 2's episode 9.1. Ika plays house with a neighbor girl who seems to think daily life is filled with drama.
* PleaseWakeUp: [[spoiler:End of "Won't You Keep It?"]]
* PoorCommunicationKills: Eiko in Season 2's episode 4.1, where she unintentionally insults Cindy, and later scares off an English speaking guy due to her use of Japanese which sounds like English words.
* PrehensileHair: Ika's hair... or tentacles, whatever they are. They're also rather [[ExpressiveHair expressive]].
* PungeonMaster: Ika/Squid Girl herself; this is exaggerated in most translations and the English dub. She doesn't do it on purpose so much as she actually thinks that's how things are pronounced. Eiko and the others quickly notice it's part of her mannerisms.
* RageQuit: Eiko does this in OVA 1.1, after being fed up with the NintendoHard games on the handheld console the three stooges develop. Unfortunately the console doesn't break, and instead smashes into the wall of the lemon shop. [[BewareTheNiceOnes Chizuru]] isn't too pleased with that...
* RazorSharpHand: Chizuru has this ability, but only demonstrates it on Squid Girl's tentacles.
* RealPlaceBackground:
** The restaurant is located on Yuigahama beach in Kamakura.
** In both the manga (Chapter 147) and the anime (Season 2, Episode 6.1), they visit Kamakura's [[http://en.wikipedia.org/wiki/K%C5%8Dtoku-in Daibutsu]].
* [[RecycledInSPACE Recycled Under The Sea]]: Inverted. This show is basically KeroroGunsou without that pesky "space" thing... Also, Squid Girl's presence is public knowledge.
** This anime can be considered as Japan's own SpongebobSquarepants, with the setting taking place on land and most of the creatures being replaced with humans. Except for the whole "becoming a network's cash cow and extending it for a bazillion seasons" thing.
*** ''Ika Musume herself'' can be considered as Japan's gender-flipped and '''moefied''' Squidward Tentacles.
* ReedRichardsIsUseless: In their pursuit of extraterrestrial life, the MIT scientists have cured cancer and created a universal translator. Unfortunately, in their single-minded pursuit of the bizarre, they don't give a crap about either of these discoveries.
* RelaxOVision: In Season 2, Episode 8.3 (Chapter 156 in the manga), Ika suffers a heat stroke and can barely move. While she [[ImagineSpot imagines]] what Sanae could do to her in that incapacitated, defenseless state, we are shown this instead. [[spoiler:Fortunately for Ika, [[EvenEvilHasStandards Even Sanae Has Standards]], and she actually refuses to take advantage of the situation.]]
* RememberedICouldFly: Ika Musume almost drowns and gets rescued by Goro. Eiko asks why she drowned, Ika Musume explains that [[ComicallyMissingThePoint her tentacles cramped because she forgot to stretch]]. After more prodding she remembers that she can't drown, because she's a squid.
** And Season 2, Episode 2.3 (Chapter 166 in the manga) reveals she ''can'' "fly" anyway.
* RequiredSecondaryPowers: It's eventually explained that the whole reason Squid Girl can pick up people and other heavy objects with her tentacles without losing her balance is that she can alter her weight with her bracelets, becoming heavy enough to anchor herself.
* RidiculouslyCuteCritter: Mini Ika Musume in 5.3 and 10.2; both are [[spoiler: products of Sanae's imagination.]] She appears again in Season 2, Episodes 4.3 [[spoiler: (as a product of the imagination of Ika herself)]] and 6.3 [[spoiler: (as a dream of Goro, who doesn't understand ''why'')]].
** A quick story in the manga has [[http://manga.animea.net/shinryaku-ika-musume-chapter-211.5.html Ika and Mini-Ika meeting for the first time]]. [[spoiler:Thanks again, Sanae.]]
* RobotMe: Mr Tokita makes one of Ika in episode 11.2 of season 2.
* SanitySlippage: Eiko when she found out Squid Girl is good at math.
* SchmuckBait: In episode 6.1 of season 2, Eiko tells Ika that the giant Buddha statue can come to life and punch bad people. Ika also sees openings in the back of the statue, which Eiko says is where a bunch of little Buddhas come out of to assist the big one. Because she doesn't know any better, Ika believes the story and is really scared to go inside, although Eiko eventually reveals she was just kidding about everything she said.
* SeriousBusiness: Season 1, Episode 12's volleyball competition gets particularly heated, culminating in [[spoiler: Chizuru stepping in as Noh Mask Rider Hannya to literally meteor smash face.]]
* ShesGotLegs: Sanae, apparently, as shown in episode 11.
** Ika as well, as shown in episode 3.
* ShipperOnDeck: Nagisa wants to pay Goro back for saving her life by trying to hook him up with Chizuru. [[spoiler:It seems to succeed ... at first]].
* ShippingGoggles - InUniverse: In episode 9, Sanae assumes Eiko's relationship with Ika is more intimate than it really is by recalling past events out of context.
* ShootTheMessenger: Chizuru destroys a "broken" scale that gave her an "unreliable" reading, shortly after seeing that worked for Eiko.
* ShoutOut:
** In episode 5.1 when Ika is proving to Eiko that she's an alien [[Film/ETTheExtraTerrestrial Ika's glowing finger touches the tip of Takeru's finger.]]
** When the scientists accidentally [[spoiler: turn the store invisible]], they bring about the wrath of Chizuru. They try to protect against her attack by shielding themselves. Harris erects an [[Anime/NeonGenesisEvangelion AT Field]], Clark brings out [[Franchise/TheLegendOfZelda Link's Hylian Shield]], and Martin throws up a [[Franchise/SuperMarioBros tortoise shell.]] Naturally, none of them work.
** Perhaps her martial prowess is a shoutout in itself? Cutting flies and tentacles BAREHANDED? Sounds supiciously like [[HokutoNoKen she is a Genyu Ken]] practitioner.
** In episode 11.1, Eiko brings a doll out of storage because it's picking up in value as a collectors item. It was part of a pair of doll toys known as [[JohnnyDepp Johnny & Depp]].
** In the background of Takeru's ''elementary school'' classroom, you can see Aho, Sethi, and Ullman's seminal computer science book "Compilers: Principles, Techniques, and Tools" (first edition). The other books on the shelf are apparently also computer science books.
** The season 2 OVA has Eiko and Ika playing a game clearly based off the original SuperMarioBros, with them as the main characters. Eiko's game is even called "Super Eiko". And the game system itself is pretty much a GameBoyMicro. And in the beginning, the mad scientist trio is playing a DS game similar to MarioKart.
** In the opening sequence there is a reference to 8-bit [[EasternRPG console RPGs]], perhaps specifically the second or third ''VideoGame/DragonQuest'' games. A sprite that resembles Ika disembarks from a boat, enters a cave, and opens three treasure chests (there's [[TrademarkFavoriteFood shrimp]] inside, of course). A console that looks a lot like an off-colour [[SEGAGenesis Sega Mega Drive/Genesis]] can also be seen near the end of the opening sequence.
** Episode 12 had [[Franchise/{{Terminator}} "I'll be back"]], [[WorldWarII "I shall return"]] and [[BarackObama "Yes we can!"]], all of them said by the MIT guys.
** In Chapter 46 of the manga, Ika Musume in her quest to become more "adult" starts watching late-night anime with [[HigurashiNoNakuKoroNi Rena]] on the screen.
** In Episode 4.2 Eiko is teaching Ika to play [[{{Columns}} Sega's Columns]]. In the original manga version (Chapter 27) it's one of the {{Gradius}} games.
** [[spoiler:Chizuru]] intervening with the Nohmen Rider stageshow as a second Nohmen Rider mirrors the originally unplanned introduction of the second KamenRider.
** Season 2, Episode 4.2: Ika and Eiko are seen playing VirtuaFighter on the off-colour [[SEGAGenesis Sega Mega Drive/Genesis]] mentioned above, complete with 32X-lookalike adapter.
** Season 2, Episode 5.2: One of the aliens imagined by [[InSeriesNickname the]] {{Three Stooges|ShoutOut}} is actually "Paranoia", a boss from Space Harrier II. At this point it seems safe to assume that the makers of the anime are ''big'' old school Sega fans.
*** As more confirmation of the above, Season 2, Episode 7.2 shows Ika playing ''VideoGame/GoldenAxe''.
*** And in Episode 8.1 it's ''VideoGame/BonanzaBros''!
*** There's also a BlandNameProduct version of [[StreetFighter Street Fighter IV]], as well as "[[SonicAndSegaAllStarsRacing Hedge]][[SonicTheHedgehog hog]] [[MarioKart Kart.]]"
** In one episode, Ika Musume copies [[CodeGeass Lelouch's pose when using the geass]]. [[http://imgur.com/G3QbiB3 Here, have a look]].
* SickEpisode:
** Ika falls ill to a Squid Girl disease. Symptoms include nausea, headaches, flushes in the face, fever, delirium, and '''''death...'''''[[spoiler:ly cravings for shrimp.]]
** A later episode has her and Sanae suffering heat stroke, with Squid Girl worrying that Sanae will recover before she does and take advantage of her in her weakened state. [[spoiler: [[EvenEvilHasStandards She doesn't.]]]]
* SingleTargetSexuality: Sanae with regard to Ika.
* SliceOfLife: Slice of Squiddly Life.
** Just don't mention the [[HeroicBSOD NAME of the trope]] around Ika, de geso!
* {{Smurfing}}: The Crunchyroll subs use this with "squid" (and give her exclamations like Squidzooks, holy tentacles, and many others) to try and convey the rather punny nature of the titles and Ika's speech.
** The English dub takes this to an extreme propensity for [[PungeonMaster ocean life puns]]. Words like "Squidy", "Krakken", "Tentacular", "Kelp", "Gilly", "Ink", "Clam", "Beak", "Jet", and numerous other words will find their way into Squid Girl's regular vocabulary. Even when you can tell the context is meant as a swear. For example, Squid Girl never says "Invasion". It's ''always'' "Inkvasion".
* SneezeCut: In episode 11.3.
* SomethingCompletelyDifferent:
** Episode 5:3, a NoDialogueEpisode about Eiko and a FunSize Ika Musume. [[spoiler:Which was [[AllJustADream all just Sanae's dream]].]]
** Happens again in episode 6.3 of Season 2.
* SpiderSense: Ika can sense certain things, e.g. Takeru watching her, other people's negative emotions or danger, when she tried to wake up Chizuru ([[MaybeMagicMaybeMundane Although the last one could be just her knowledge that Chizuru is dangerous]]).
* SpitTake:
** Eiko does this without even drinking anything in episode 5.
** Goro does it in OVA 2.2 after his mother teases him a little bit with Chizuru.
* [[FishOutOfWater Squid Out Of Water]]: the premise.
* [[{{Squee}} "Squii"]]: Or in Japanese, "gesho".
* StalkingIsLove: Sanae shows her "love" for Ika Musume by ''collecting an entire album full of photos of her''. Goro also collects pictures of Chizuru.
* [[StatusQuoIsGod Status Quo is...Chizuru]]: If she has anything to say about it, Ika will ''NEVER'' work off her debt, and thus ''NEVER'' begin her invasion of Earth. Chizuru will see to it that Ika [[ItMakesSenseInContext spends the rest of her natural life helping out at the Lemon beach house]]...
** This also extends to most of the characters themselves, such as Sanae tearfully letting her obsession with Ika go, only to revert right back to it before the end of the episode. And later [[ShrinkingViolet Ayumi]] learns to be more confident thanks to a pair of brass knuckles Chizuru let her use (causing men to be really fearful of her), only to have her dad immediately shoot her confidence right back down towards the end of the episode.
* SurprisinglyGoodEnglish: Ika picks it up very quickly in episode 4.1 of season 2, [[BookDumb Eiko]] seems to be the only one that struggles with it at all.
* SuspiciouslySpecificDenial: Sanae in episode 1 of season 2.
--> Sanae: [[BlatantLies I'm not a suspicious person!]] I wasn't trying to eavesdrop on your conversation or anything! Not at all!
** Or Chizuru's claim that her pedometer with cute display-animation is [[BlatantLies definitely not for a diet]].
* TakeOverTheWorld: Supposedly Ika's goal. How she's going to achieve that is another matter. Eiko informs her on what "taking over the world" really entails.
* {{Tanabata}}: Ika tries to exploit it for as many wishes as she can. Kiyomi doesn't tell anyone, but she wishes [[spoiler: for a bigger chest]]. In the end, Ika ultimately decides that [[spoiler:after she finds out that some people (Chizuru, Sanae, Cindy, Harris, Clark, and Martin) wish that they ''have'' her, she wants to be safe.]]
* TentacleRope: Ika does this to Eiko when she wanders into Eiko's room and falls asleep there.
* TeruTeruBozu: These and Ika's art skills are the focus of episode 10.1.
* TestOfCourage:
** Ika is not afraid, because, not being raised in human society, she has no idea that she's supposed to be scared. Goro, however, is terrified.
** They take another one in chapter 100 with the party consisting of Eiko, Ika, Nagisa, and Cindy, this time in a tunnel instead of a graveyard. Unfortunately there are a whole lot of problems with this venture (Eiko insisted on taking only one flashlight which runs out of batteries, Ika Musume's light is too bright, etc.) so they call it off. Only problem is, Cindy's missing. Cue Cindy surrounded by ghosts. Cue ColorFailure for everyone else.
* ThemeTuneCameo:
** In the second episode's second segment during the second season, "Shinryaku no Susume" (the first season's opening theme) can be heard on the radio at the Lemon.
** Kiyomi sings it at a karaoke in Season 2, Episode 7.3, too.
* ThereIsAnother: Mysteriously in the manga chapter [[spoiler:"Can I Bother You?".]] In the anime, it's [[spoiler: episode 12.]]
** In both cases, the "other" is [[spoiler:[[PunnyName Tanabe Kozue]].]] Like Ika, she has an unusual hat, [[spoiler:but hers is round and orange. And [[MeaningfulName the first syllables of her name are "tako", meaning octopus]]]]. She finds it amusing that Ika didn't bother to come up with a less obvious name than "Ika Musume"/"Squid Girl". [[spoiler: She appears again in the Season 2 finale.]]
* ThreeShorts: This is because the original manga is basically a "gag-a-day" comic, with very short chapters (usually less than ten pages long).
* ThrowTheDogABone: Ika's "takeover" of Eiko's high school is the closest thing to actual invading she's accomplished. Though it also reveals that she hasn't thought through what she intends to do ''after'' her invasion succeeds.
* TickleTorture: All of chapter 81 (Season 2, episode 4.2 in the anime). Ika is eager to take it to [[FetishFuel extreme levels]], but forgets that conquering humanity with tickling doesn't work if you're more ticklish than everyone else.
** She doesn't realize this until she attacks ''Chizuru'', of all people -- only to be told "You ''missed'' my weak spot."
** She already used it on Eiko in episode 7, as well as Cindy and the MIT trio in episode 11 of the first season of the anime, so this has become an AdaptationInducedPlotHole.
* TimeSkip: In the final episode of season one, a year passes [[spoiler:after Ika "returns" to the sea. Of course, she comes back.]]
* TimeTravel: Ika Musume breaks Takeru's RC buggy. The Three Stooges repair it... And when Takeru wants to give it a test ride, the buggy [[http://manga.animea.net/shinryaku-ika-musume-chapter-99-page-8.html breaks a window]] and (according to a post-chapter panel) [[http://manga.animea.net/shinryaku-ika-musume-chapter-99-page-9.html travels back in time to the age of the dinosaurs]].
* {{Tomboy}}: Nagisa
** With her tough, competitive attitude, playfulness, how well she gets along with Takeru compared to the other girls, and her general silliness, you could argue Ika herself acts more like a boy than a girl.
* TonkaTough: The legendary toughness of Creator/{{Nintendo}}, err... [[BlandNameProduct Mintendo products]] get referenced a couple of times in the manga. The first was when the three idiots express surprise that they accidentally broke a DS, causing them to create an even tougher portable gaming system. The second was when Cindy tries to break a Family Computer in frustration, only to stub her toe in the process without damaging the console.
* TooKinkyToTorture: Sanae
* TouchOfDeath: Chizuru accidentally almost did this to Ika Musume, when she wanted to fulfill her wish to grow taller, but pressed the wrong pressure point and gave her a NearDeathExperience.
* TrademarkFavoriteFood: Ika loves shrimp, much like an actual squid.
* TrueArtIsIncomprehensible: Used In Universe in episode 10.1 when Eiko gets Ika Musume to draw a self portrait.
* UnexplainedRecovery: The beach house Lemon is destroyed at one point, but it's back next chapter no worse for wear. There's no explanation given [[http://manga.animea.net/shinryaku-ika-musume-chapter-95-page-10.html unless you count the omake]]...
* UnusualEuphemism: The subtitles for the anime give Ika quite the potty mouth. However all of her curses are squid puns (ala TeenageMutantNinjaTurtles and turtle puns) so the show still remains relatively tame.
* UnusuallyUninterestingSight: None of the customers of the Lemon Beach House seem to mind getting served by a half human / half squid hybrid creature which carries their food and drinks with its tentacles.
* VerbalTic: Ika frequently ends sentences with "de geso" ("geso" meaning "squid tentacles" in culinary terms) and "jana'''i ka'''".
** And in episode 12 she changes it to "dawa".
** In the dub, she loses her squiddy mannerisms, and "dawa" is changed to "You Know?" Lampshaded by Eiko later in the episode.
* VillainProtagonist: Though it's ''very'' easy to forget, considering just how cute Ika Musume is.
** That and the purpose of her "invasion". While not the smartest way to go about it, [[AntiVillain her motivation for doing so is valid]].
* VomitIndiscretionShot: It's eventually revealed that Squid Girl can vomit ink at will. PlayedForLaughs whenever it happens.
* WalkingShirtlessScene: Goro. Justified since he's a lifeguard. Coincidentally, [[Manga/FairyTail Gray]], who's also included in this trope, is voiced by the same [[Creator/YuuichiNakamura voice actor]].
* WalkingSwimsuitScene: Cindy and Tomomi, as well as others; justified since this is a beach series.
* WaterfallPuke: Played with. Though not actually vomit, Ika-Musume replicates the visual perfectly when she horks up some ink to [[http://stream1.gifsoup.com/view2/1269887/squid-girl-ink-o.gif make squid ink pasta.]]
-->'''Eiko''': "How can you eat that after watching her vomit?"
* WelcomeToCorneria: The RPG Eiko and Squid Girl play has this. They meet [=NPC=]s that looks a lot like Takeru and Sanae, and they just repeat themselves over and over.
* WhatBeautifulEyes: As Chizuru has EyesAlwaysClosed, she might count for this trope in [[http://c.mfcdn.net/store/manga/5349/01-015.0/compressed/f128.jpg this]] kind of moments.
* WhatCouldHaveBeen: Invoked in ep 5-3, which answers the question of what would happen if Ika and Eiko had initially gotten on better terms. The answer? [[spoiler:It ends in a TearJerker as [[WhoWantsToLiveForever Ika will most certainly outlive any human]].]]
* WholesomeCrossdresser: Takeru and Nagisa, apparently.
* WhyDidItHaveToBeSnakes:
** Ika is terrified of her greatest natural predators, orcas and sharks, even in inflatable toy form. Also the banana in inflatable toy form, since she's never actually seen a banana.
** She's also scared of Chizuru [[BewareTheNiceOnes (but she has very good reasons to be)]].
** Goro's not afraid of near-drowning -- as a lifeguard, he takes risks regularly -- but he is absolutely ''terrified'' of ghosts. Although it takes a lot to get him to admit it in front of Chizuru.
* WingdingEyes: A common reaction of both Cindy and Sanae to Ika Musume, and a common reaction of Ika Musume to [[TrademarkFavoriteFood shrimp]].
* WorkOffTheDebt: Even after the wall is repaired, Ika will still have to work 5 or 6 years to pay it off. She did find a large bill, but Chizuru persuaded Ika to use it on a shopping trip, keeping her in Lemon's employment.
-->'''Ika''': "What kind of lame wage are you paying me, de geso?"
* XMeetsY: This anime is basically ''Manga/KeroroGunsou'' meets ''Anime/{{Ponyo}}''
----