[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/squidgirl.png]]

->''"This invader comes from under the sea\\
She's got a grudge against humanity\\
To subjugate the surface, that's what she wants\\
But she's stuck waiting tables at this restaurant"''
-->-- FilkSong "[[https://thirdimpact.bandcamp.com/track/squid-girl Squid Girl]]" by Third Impact

''Shinryaku! Ika Musume -The invader comes from the bottom of the sea!-'', known in the English-speaking world as simply ''Squid Girl'', is a manga by Masahiro Anbe that was serialized in ''[[Magazine/ShonenChampion Weekly Shonen Champion]]'' from 2007 to 2016. The manga was adapted into a {{twelve episode anime}} by Creator/{{Diomedea}} in Fall 2010. It was initially licensed and dubbed by Creator/MediaBlasters, but the American license is now held by Creator/SentaiFilmworks.

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.

A second season of the anime, titled ''Shinryaku!? Ika Musume'', aired in Fall 2011.

''Ika Musume'' enjoyed some additional publicity in the summer of 2015, when fandom jokes and the mangaka's own love for the game led to a ''Squid Girl'' brand costume set being added to Creator/{{Nintendo}}'s ''VideoGame/Splatoon1''.

After the manga concluded, the author moved on to ''Manga/GatherMysteryResearchClub''.

Both seasons can be watched on [[http://www.crunchyroll.com/squid-girl Crunchyroll]] (subbed), and the first season is also available on Creator/{{Netflix}} (dubbed).

----
!!Tropes, de geso!

* 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".
* 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 would have caught the real Squid Girl if it hadn't been for its power cord stopping it.
* AdaptationExpansion: Typical manga chapters 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 real reason (her bracelets) isn't revealed till much later in chapter 166. Episode 2-3 of the second season goes straight from one to the other.
* AdaptationalJerkass: "Won't You Go to Elementary School?" not only adapts the manga chapter of the same name, it also includes a later, unrelated chapter "Won't You Kick?" where Squid Girl plays soccer with Takeru's friends. In order to weld the stories, Yuta and Takeru's other friends become jerks to force a conflict. Oddly, they still keep the manga's conclusion where Yuta and co. are worried about bruising Squid Girl's ego, even though it doesn't track with their adaptional personality change.
* AlertnessBlink: Shown in the TitleSequence 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 awesome 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.
* AnimalsHateHim: Downplayed; Ika doesn't have a lot of luck with stray dogs or Sanae's pet dog Alex (In the latter case, because he's jealous of her), but other dogs like Ayumi's are fine with her.
* 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 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.
* AscendedExtra: Ayano Watanabe was a bit part in the manga. The anime makes her the fifth member of Kiyomi's circle of friends.
* AscendedMeme: "You gotta be squidding me!" actually made it into the dub.
* ArtisticLicenseBiology: Ika has not been revealed to have any suction cups.
* 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.
* AttentionDeficitOohShiny: One episode of the anime shows Ika learning a series of exercises that she doesn't understand, and during the rest of the ensuing episode, she constantly breaks things and causes problems because she can't stop trying to imitate them, resulting in her causing tons of problems such as throwing a bowl at Chizuru, and after apologizing she begins trying to continue the poses, only coming back to reality when Chizuru slams a knife into a cutting board out of rage, causing Ika to run in terror.
* BadassAdorable:
** Ika-Musume, when she actually tries; her tentacles can move at supersonic speeds and are able to easily punch through concrete.
** To Chizuru, the trope comes ''as natural as breathing air''. She's a kind and adorable young woman, but she has amazing SuperStrength and can cut Ika's tentacles in mid-flight with her bare hands, among other crazy feats. Which is suspicious enough to Cindy and her team that they try to get a lock of Chizuru's hair for analysis.
** Sanae is a downplayed example; she may not have any fighting abilities, but her speed and reflexes are much better than any teenage girl's should be. She's also an adorable GenkiGirl with an unhealthy but cute obsession for Ika.
* BadassArmFold: Ika sports one of these in episode 1, complete with manic grin and red-and-black cool-looking background.
* BaffledByOwnBiology: The eponymous character is mystified by the concept of "ticklishness", which Eiko then helpfully demonstrates by telling Squid Girl to lift her arms, and then proceeding to tickle her. Squid Girl is perplexed as to why she was laughing when she didn't find it at all funny. She's also perplexed at the inability to cause the sensation in herself when she tries to do what Eiko did.
* BaitAndSwitch: A common occurrence. Among a few examples:
** When Ika meets Kiyomi, she asks her to pretend to be her friend for the time being, so that the truth about her failed doorbell ditching doesn't get out. Kiyomi refuses... preferring to become Ika's friend ''for real''.
** When Eiko, Ika and Takeru start handling all the household chores, this leaves Chizuru with a lot more time for herself, but also very restless. Then Ika breaks a dish accidentally and gets super scared as Chizuru makes a mad dash towards her... then Chizuru starts happily cleaning the floor, feeling a lot better now that she had ''something'' to do.
** In the final chapter, [[spoiler:Ika is free from work after having repaid the hole she busted at the start of the series, and starts her invasion proper by destroying the Lemon Beach House. But then it's revealed she wasn't aiming to invade like she claimed, but deliberately get ''another'', much bigger debt as an excuse to stay]].
* 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.
* BareHandedBladeBlock: In chapter 238, as a sign that was blown off by the wind was headed straight for Ika, she stopped it with her tentacles in this way.
* BaseballEpisode: Episode 10.3, where Ika joins Kiyomi's baseball team.
* BattleAura: For [[SeriousBusiness building sandcastles.]]
* BeamOWar: Done in Season 2's Episode 11: Ika Musume faces off against a machine meant to replace her and the fight devolves into an ink spitting battle.
* BeeAfraid: When Ika hits a sunflower in chapter 141 and a bee stings her nose.
* 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.]]
* BewareTheSillyOnes: The few times they're antagonistic, the Three Stooges are usually too bumbling to get anywhere. When they get serious, however, they can be surprisingly competent; chapter 269 has them come surprisingly close to kidnapping Ika, until Chizuru saved her and beat the crap out of them.
* {{Bifauxnen}}: In chapter 148/Episode 2 of season 2, Eiko makes Nagisa dress up as a guy to attract more female customers.
* BigBallOfViolence: In chapter 154, Sanae's dog Alex engages in one with a stray dog to get one of Ika's lost sandals back. It works, but the sandal is messed up in the process.
* 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.
** She does it again later on, this time to convince Goro to serve as a training partner so she can teach Ayumi self-defense. Again, it works.
** Eiko gains a Bishie Sparkle whenever she is force fed food covered in Squid Girl's ink.
* 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 up to eleven.
** Goro's mom, so much. Her home meals are enough to feed an entire family, and she can win a restaurant's regular eating challenge so casually that can basically eat there for free every time she visits.
** Chizuru is a downplayed example, in that while she eats a lot, she remains careful not to eat ''too'' much, and makes up for what she does eat with lots of exercising. Nonetheless, her bigger-than-usual appetite is the source of her WeightWoe.
* BlandNameProduct:
** In episode 9 Ika and Kiyomi play ''[[Franchise/StreetFighter Stocking Fighter IV]]'' and Ika picks Dhalsim-expy Mr. Yoga.
** And then they get a copy of ''[[VideoGame/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. [[Administrivia/TropesAreTools 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.
** In Chapter 52 of the manga, "Won't you Economize?", the gang decides to cut down on unnecessary resources to help the environment. This goes from TV to the AC to lighting to ink. No, not squid ink. "Ink," as in ''the ink that the manga is printed with''. A blank panel shows up, followed by Eiko bringing back everything with this wonderful line:
-->'''Eiko:''' THAT'S ENOUGH! ARE YOU TRYING TO CUT DOWN ON OUR READERS TOO!?
* 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...]]
* 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.
* CaptainObvious: From chapter 212:
--> '''Nagisa''': "If you're fine [talking] with the squid person [because she's not human], what do you think she is? An alien? A youkai?"
--> '''Ayumi''': "A squid."
* 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.
--> '''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.
* ClingySleepers: Squid Girl will often cling to Eiko's bare leg with her tentacles in her sleep. Once this resulted with them somehow trading spaces between the bed and the floor, with Eiko firmly in Squid Girl's tentacles, the sleeping cephalopod mistaking Eiko for a delicious shrimp and attempting to chow down.
* 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".
* ComedicWorkSeriousScene: While the show is mostly funny with Squid Girl's [[IneffectualSympatheticVillain ineffectual attempts at world domination]], there are some serious moments:
** The very first episode is comedic when Squid Girl arrives at the beach and tries to be threatening, but the second-to-last segment ends on a rather serious note. Takeru [[PaperThinDisguise wears a squid hat]] so he can become Squid Girl's partner, but then a fan blows the hat off his head and Squid Girl believes this means the "squid" she met is dead, so she puts the hat out to rest in the ocean and mourns for it.
** Most of the segments in Episode 5 are comical, and the final segment is also silly and cute with Eiko and Mini Squid Girl bonding together. Then an elderly Eiko dies [[DeathWail as Mini Squid Girl screams in anguish]]. Then [[MoodWhiplash it goes right back to being funny]] when Sanae reveals that [[AllJustADream the events were a dream she had]] and [[MadAtADream she's annoyed and jealous that Eiko was the one to spend time with Squid Girl instead of her]].
** Episode 8 has a segment about Squid Girl's [[CompanionCube shenanigans with an umbrella]], but then a car runs it over and destroys it. Devastated, Squid Girl clings to the umbrella and [[MourningAnObject openly weeps over it.]]
* ComicBookTime:
** Per the manga finale, all 418 chapters take place during a single summer vacation, despite the fact that there are more chapters than days in a year and many chapters span multiple days.
** In the afterword to chapter 418, which came out 11 years after the manga started, Anbe says he wants to make three sequels chronicling Ika Musume's life in every season. Assuming they're the same length as Squid Girl, that adds up to a whopping ''44 years'' to cover a single year of story.
** [[AvertedTrope Averted]] in the anime, which only ran for 81 segments and had a one-year time skip in the season 1 finale.
* 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.
** Ika's attempt to make a "cup that goes ting-ting" (a wind chime) creates a whole chain of these. Takeru thought she wanted to make a string telephone, a little boy saw the string telephone and thought Ika wanted to make pokkuri, and Sanae saw the pokkuri and thought Ika wanted to play Cho-Han. Eiko lampshades it at the end of the chapter, wondering how Ika got so far from the wind chime.
* CompanionCube:
** Ika's Umbrella in Episode 8. [[spoiler:She doesn't give it up, however, in the Couch Gag.]]
** To a lesser extent, Eiko's Famicom, which she refers to as her "old buddy" since she was a child. When it broke, she was so saddened she buried it in the garden as if it were a pet, complete with grave marker.
* 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]].
* CrystalBallScheduling: ''Keiketsu! Uchuujin-kun'', an anime Cindy likes about an alien who attempts to invade Earth and gets press-ganged into working at a restaurant.
* 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.
** In chapter 361, Ika vs Goro's mom, in a sumo wrestling tournament to win Matsusaka beef. Ika gets pushed out of the ring almost immediately. [[spoiler:Though it works out anyway since Goro's mom decides to share the beef with the Aizawa family anyway, since she felt a bit guilty about it.]]
* CurtainsMatchTheWindow: Common in the cast, Ika chief among them.
* CuteMonsterGirl: Ika Musume herself is a cute squid girl. [[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...]]
* 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.
* DamnYouMuscleMemory:
** In chapter 178, Ayumi learns self-defense from Chizuru. At the end of the chapter, when Ayumi's father goes to pick his daughter up, she's trained so much that she reflexively throws him on his ass without realizing it.
** In chapter 383, Chizuru puts Sanae through TrainingFromHell to improve the latter's cooking. Unfortunately for Sanae, she reflexively breaks the table with a punch just as she was about to serve Ika a plate of her cooking.
* DancePartyEnding: The final credits of Season 2.
* DeadpanDoorShut: Squid Girl, fresh off eating a mountain of shrimp she'd bought with reward money, receives a package. She and Eiko open the box to find [[AbhorrentAdmirer Sanae]] inside, on the verge of passing out due to lack of fresh air and wearing a giant shrimp costume. Eiko asks if Squid Girl is still hungry for shrimp; Squid Girl shakes her head slowly as they close up the box again.
* 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. Squid Girl downsizes her plans a little and decides to just take over the lemon shop first, although she fails at that as well. 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.
* DiegeticSoundtrackUsage:
** 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.
* DingDongDitchDistraction: Ika tries this. She's interrupted before she can run away and ends up meeting a new friend.
* 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.
* DramaticShattering: A variation. In one chapter, Kiyomi decides to eat the entire tray of Sanae's awful cookies, so as to protect Sanae's feelings. It resulted in Kiyomi's glasses to ''spontaneously shatter'' from the foul taste and caused the poor girl to faint.
* DreamSequence: The [[spoiler: Mini-Ika episodes]] turn out to be these, the first of Sanae, and the second of ''Goro'' of all people.
* DrunkOnMilk: Backstage, the hero show presenter chugs a plastic bottle down hard and exhales with gusto to drink her worries away...with ''Coca-Cola''.
* 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.
* {{Expy}}: A large proportion of the ''Literature/ACertainMagicalIndex'' 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 [[https://www.youtube.com/watch?v=VSY69ehDMdE the third episode]] of "To Aru Majutsu no Index-tan" (a DVD extra of Literature/ACertainMagicalIndex), 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.
* FaceFault: Chapter 321 has what might just be the most bodacious Face Fault ever committed to print. Nagisa, while cresting a wave on her surfboard, spots Squid Girl making a little swan boat out of her tentacles. Cue Nagisa flinging herself backwards and drooping like a stone from atop a twenty-foot wave.
* 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.
* FairCop: Keiko Furukawa is such an adorable young policewoman that when she wore a bikini to stand out less, she ended up standing out ''more'' because customers were now attracted to her beauty.
* FairPlayWhodunnit: In chapter 385, if you pay attention, it's easy to figure out who scribbled "useless teacher" on Aiko-sensei's face while she was passed out. [[spoiler: Her sister denies having written it, but she accidentally lets slip she knows what it says despite never having seen it.]]
* 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, so by process of elimination...
* FanDisservice: Chizuru stripping the three male scientists.
* FeminineLegSwish: Season 2, Episode 4-B, "You Th-INK You Can Stop It!?", Squid girl is lying on the floor of Eiko's room, reading, and kicking her feet back and forth in a scissoring motion, showcasing her childish tendencies. However, she is also waving her tentacles around absently, which causes her to inadvertently tickle Eiko's bare feet, which is how Squid Girl learns about tickling.
* FeminineWomenCanCook: Subverted with Nagisa, who makes a surprisingly good vegetable soup. She ends up trying to hide it, 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! Only problem, the watermelons' insides were jet black, though Sanae claimed they were good regardless.
* 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 curiosity about life on the surface world), season 2 seems to have started making her more ''Manga/SgtFrog''-like. For instance, in episode 9-2, Ika is blatantly portrayed as completely missing the point of using a bag and planner.
* FlashStep: Chizuru demonstrates this ability when angered by Ika in Season 2 Episode 11. In the manga, Chizuru is even shown performing a flash step [[{{Sleepwalking}} while in a deep sleep]].
* 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.
* FormulaBreakingEpisode: Episode 5:3, a NoDialogueEpisode about Eiko and a FunSize Ika Musume. [[spoiler:Which was [[AllJustADream all just Sanae's dream]].]]
* FoulMedicine: In episode 5, Mini Squid Girl has a BalloonBelly from eating a lot of shrimp and this puts her in some pain, so Eiko attempts to hand her a pill. Mini Squid Girl refuses to open her mouth until Eiko [[FriendlyTickleTorture tickles her ribs]] and makes her laugh. Subverted, however, as Mini Squid Girl doesn't appear to mind the taste once Eiko tosses it into her mouth.
* 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: Mini Ika Musume.
* FunWithForeignLanguages: Season 2, Episode 4.1, particularly the hilarious InMyLanguageThatSoundsLike thing between Cindy and Eiko.
* FunnyOctopus:
** The eponymous IneffectualSympatheticVillain [[VillainProtagonist Protagonist]] Squid Girl is a humanoid (whether she has a backbone is not mentioned). She has several squid traits, specifically Bioluminescence, CombatTentacles, the ability to spit (or WaterfallPuke) ink, and TentacleRope.
** Ironically the ''actual'' octopus girl, Kozue Tanabe, is pretty laidback and displays none of the Funny Octopus traits.
* FunWithAcronyms: In the manga, Cindy works for [=ARIEL=], the American Research Institute for Extraterrestrial Life.
* GainaxEnding: Chapter 182, "Isn't it Air [_____]?" The chapter is about Squid Girl becoming fascinated by air guitar and other kinds of miming. It culminates with her pretending to show hospitality towards her "air friend", Air-ko. Air-ko then spontaneously starts interacting with the environment, freaking Squid Girl and Eiko out. The chapter immediately ends with a note stating the experience caused Squid Girl to swear off Air [_____] forever.
* 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.
** One episode of the anime exemplifies this when she shows she is so skilled at math, that she can solve complicated math problems despite never having been visibly shown learning mathematics at any given point. We then see her common sense at work, as she fails to realize nobody cares except Eiko, and Eiko only cares because she wants to ace a test.
* GenkiGirl: Ika and Sanae.
* GilliganCut: In one chapter, Gorou gets tickets to a pool resort from his mother and decides to invite Chizuru. The next panel shows that he chickened out and invited everyone in the Aizawa house ''but'' Chizuru. Eiko lampshades it by calling him a coward, though it's subverted when Chizuru comes in on her own anyway.
* GodivaHair: at one panel when Ika took a bath.
* 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.
* GrinOfRage: In season 2, episode 11, after Squid Girl implies that Chizuru is an alien, Chizuru is clearly furious, but she smiles and whispers into Squid Girl's ear that she'd like to tell her something before she drags her to another room. Squid Girl remains oblivious to Chizuru's rage, however.
* HeroStageShow: Squid Girl is distressed to learn that "Devil Squid" is supposed to be the bad guy in the beach hero show, and decides to even the odds.
* HopelessSuitor: Sanae with regard to Ika.
* 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.
* HurtFootHop: In one chapter, Ika gets tired of hopping on one foot after the stray dog that stole one of her sandals, and instead decides to run. Bad idea when the summer heat makes the pavement hot as lava.
* HypnoPendulum: Sanae tries using one to hypnotize Ika into loving her in one chapter. Only problem, it fails, and she looks so desperate in trying to make it work that everyone she does it on has to play along; even ''her pet dog'' was faking it.
* 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?!"
* IChooseToStay: [[spoiler:In the finale, Ika chooses to stay on the surface, but exclaims it in a strange way by destroying the Lemon Beach House to gain a much bigger dept than before. However, it turned out to be for naught, since Chizuru pointed out summer is over, and the beach house will be closing anyway.]]
* 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.
* IdolSinger: In chapter 255, Eiko concocts a plan to help Ayumi with her shyness by making her an idol. She gets over her crippling "can't-talk-to-people" issue by imagining her fawning male fans are [[ImagineTheAudienceNaked bipedal pigs]].
* 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.
* ImportantHaircut: [[spoiler: Ika in episode 12. [[FridgeBrilliance Interestingly, she cuts her tentacles at the same angle as Eiko's hair]].]]
* INeverSaidItWasPoison: Chapter 385. [[spoiler: Nagisa Saito knows what the rude message scribbled on her sister's face says, despite never bring told.]] Squid Girl figures it out, but since she's doing all the detective cliches, she pretends to get murdered and writes the culprit's initials on the floor with her ink. Unfortunately, Keiko misreads them and takes [[spoiler: Sanae Nagatsuki]] in for questioning instead.
* 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.
* {{Irony}}: In chapter 211, Squid Girl is finally alone with the meek Ayumi and decides to scare her so she'll be cowed by "the invader from the sea", like Nagisa. However, Ayumi unleashes a wall of text apologizing for her past actions and explains that although she has problems talking to people, Squid Girl isn't a "person" so she feels fine. The next chapter, Nagisa sees Ayumi casually chatting to Squid Girl and assumes that she has been cowed into submission by the invader.
* JerkassBall: In chapter 59, Chizuru decides to implement a KarmaMeter for Squid Girl just for amusement's sake. But when Squid Girl is on the cusp of winning her prize (a lobster dinner) with good deeds, Chizuru decides it's not entertaining enough and punishes her harshly for minor infractions, leaving Squid Girl a nervous wreck who's afraid to do good deeds out of fear they'll be misinterpreted. Usually, in situations like these, Chizuru will take some responsibility for being TheGadfly and do something nice to make up for it. Here, she just callously asks Squid Girl if she wants to try again. Squid Girl, thinking her failure is her own fault and not Chizuru moving the goalposts on her, politely declines.
* {{Kimodameshi}}: During Episode 3.1 of Season 1, a traditional "test of courage" game is played, complete with [[HitodamaLight floating ghost flames]].
* LapPillow: One chapter has Ika try and find the best pillow in the world, so she asks Goro for his opinion; naturally, he thinks Chizuru's lap is the one. Chizuru does let Ika sleep on her lap, but unfortunately, Ika's too scared of her to keep it up.
* LastEpisodeNewCharacter
* LaughingMad: Eiko, when she finds out Squid Girl is far, far better at math than her.
* LawyerFriendlyCameo: [[Franchise/KamenRider Nohmen Rider]]. Ika, of course, roots for the Dr. Shinigami-like squid monster.
* LeaningOnTheFourthWall:
** In chapter 75, Ika draws an amazingly realistic portrait of Takeru. Chizuru quips it looks like it's from another dimension. It has proper shading and volume, so she's quite right--it has a third dimension, unlike their flat manga faces. Later in the chapter, Takeru tries to draw Ika, but he complains that it turned out too much like a manga. The picture is just Ika, exactly as she appears to us. Ika then complains her face looks too simplistic.
** In chapter 95.5, the Aizawas discuss maturing and what they should give up as they get older. Eiko says she might graduate from ''Weekly Shonen Champion'', since it's a manga magazine for boys. A concerned Chizuru says that the female demographic is also important. ''Weekly Shonen Champion'' is the magazine that publishes ''Squid Girl''.
** In chapter 211, after the normally shy Ayumi unleashes a torrent of dialogue, Squid Girl quips she's trying to make up for lost time in a single panel.
* LethalChef: Sanae; to her dismay, as she genuinely tries to make good food to win Ika over. The standout example is her homemade cookies from chapter 285, which exuded a menacing aura.
* LifeguardFanservice: Goro Arashiyama, Tatsui Isozaki, and all the rest of the Lifesavers are tall, muscular men who [[WalkingShirtlessScene tend to go around in just their swimming trunks]], showing off their pecs and abs, and there's an audible gleam to their teeth when they smile. Their Fanservice is [[DownplayedTrope Downplayed]], though, as Goro has SingleTargetSexuality for Chizuru, and Isozaki usually strikes out with the ladies he tries to flirt with, particularly the ShrinkingViolet Ayumi, though that may have more to do with her social anxiety than anything against Isozaki in particular. The rest of the Lifesavers in the show are shown in the background and go unnamed.
* LightEmUp: Like certain species of squid, Ika's able to make herself luminous. LightIsNotGood, since there is the fact of Ika being a VillainProtagonist.
* LittleBitBeastly: Ika herself. Also, the apparent [[spoiler:octopus girl]] Ika meets at the beach.
* 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".
** In one chapter, Ika and the Invasion Club try to win at a prize-shooting game during a summer festival. After the other girls fail, Ika gets one by using her tentacles as hands and shooting the prize point blank. The owner tries to protest, but is forced to relent after Ika points out he rigged the game (By sticking the prizes to the stall via tape and making the gun weaker).
** Chapter 225 has an initially unintended example: when Isozaki and Eiko play a fighting game at the arcade together, the former challenges the latter to introduce him to a girl if he wins. When he does win, Eiko comes to the date herself, since everyone else she asked refused. The "date" turns into Eiko and Isozaki playing more games at the arcade.
* 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).
* MadeOfIndestructium: 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.
* MeaningfulAppearance: 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''''' because, for all intents and purposes, it's ''part of her skull''. She tries to forcibly pull the hat off in Chapter 106 (Season 2, Episode 7.2 in the anime), 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.
* 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. 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.]]
* MilestoneCelebration: [[invoked]][[AvertedTrope Averted]] for the one hundredth and two hundredth chapters, which are just normal SliceOfLife, then [[SubvertedTrope subverted]] for chapter 300. Chizuru throws a big party at the Lemon without explanation, and all the attendees are too polite to ask what they're celebrating...until she brings out a big cake with "300" written on it, leading Squid Girl to boisterously surmise that it's Chizuru's 300th birthday. The chapter ends with Chizuru leading the unsuspecting Squid Girl away for a ''private party''.
* MistakenForRomance: In episode 9, Sanae assumes Eiko's relationship with Ika is more intimate than it really is by recalling past events out of context.
* 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 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.
* MusclesAreMeaningless: Chizuru has the slender build of a young woman who is mildly athletic. She also has been shown to have super-human levels of strength.
* MysteriousPast: Despite starring in 418 chapters, Squid Girl's pre-invasion life has never been shown or told from a handful of cryptic hints:
** They have incredible technology, able to make weight-altering bracelets and self-healing clothing.
** Her father is apparently lazy.
** In chapter 327, she mentions that the bottom of the sea wasn't dark, because "everybody was glowing all the time, so it was actually pretty bright".
* 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.
* NightmareFace:
** Chizuru, most of the time when she opens her eyes. However, she looks normal, even cute, when she opens them without malicious intent; the best example being when she wore 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 UsefulNotes/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.
* OneDegreeOfSeparation: After Anbe brought back the [[NoNameGiven unnamed]] hero show host as a kindergarten teacher and introduced clumsy cop Keiko, he then rerconned them and nurse Ruka into being high school classmates.
* 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 Creator/{{Sega}} games,) but it also plays a BlandNameProduct version of ''VideoGame/StreetFighterIV''.
* PaintingTheMedium: In chapter 119, Ika becomes so obsessed with the "Find the mistakes" game that she tries finding some in people around her. According to her, Chizuru's mistake is that she's actually a boy in disguise, since there's no way a normal girl could have superhuman strength like that. Chizuru's immediate reaction isn't shown, but seeing as Ika's speech bubble conveniently hides Chizuru's face, and judging from Eiko's scared expression, it's definitely not pretty.
* 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. [[SugarWiki/FunnyMoments 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''.
* 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 demonstrates the ability to cut things with her bare hand. In the anime she only demonstrates the ability on Squid Girl's tentacles (the manga version has her holding a knife while doing these actions, making the anime version even ''more'' awesome) but later on in the manga she uses her bare hand to cut a weapon-grade watermelon that the three stooges had enhanced to resist a chainsaw.
* RealAfterAll:
** Goro spends most of chapter 232 freaking out over a ghost story Eiko told him, involving a girl who disappeared while looking for her red sandal. After Eiko tells him the story was made up, he finally starts to calm down, but then we see a suspicious lone red sandal drifting ashore.
** In one chapter, the gang freaks out over a supposed ghost picture, which turns out to just be Takeru's hand as he waved to try and be in the picture. But the end shows that there's also a suspicious, disembodied grinning face in there too...
* 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 [[https://www.japan-guide.com/e/e3100.html Daibutsu]].
* RecycledInSPACE: This show is basically ''Manga/SgtFrog'' '''NOT''' in space. Also, Squid Girl's presence is public knowledge, but [[UnusuallyUninterestingSight nobody seems to care.]]
* 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, [[EveryoneHasStandards 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 Ika and Mini-Ika meeting for the first time. [[spoiler:Thanks again, Sanae.]]
* RobotDog: The focus of chapter 257, where the Aizawas get a robot called Marcie dog from the Three Stooges. Because she's a robot, she can transform and can't eat, but she's so lifelike that she's an otherwise completely ordinary dog. [[spoiler:The chapter ends on a bittersweet note as Marcie "dies" when Takeru couldn't help feeding her food, since she seemed to really want some, but Ika caused her to transform, bringing her somewhat back to life (Eiko notes the dog they knew and loved is definitely dead).]]
* 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.]]
** In general, badminton is the best way to get Kiyomi's competitive spirit to fire up. This is downplayed as Kiyomi remains sweet anyway, but she does take badminton seriously.
* 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]].
* 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 suspiciously like [[Manga/FistOfTheNorthStar 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 collector's item. It was part of a pair of doll toys known as [[Creator/JohnnyDepp Johnny & Depp]].
** At the very beginning of episode 11.2, [[Manga/RanmaOneHalf Nabiki and Kasumi Tendou]] are sitting at a table in Lemon House.
** 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 ''VideoGame/SuperMarioBros1'', with them as the main characters. Eiko's game is even called "Super Eiko". And the game system itself is pretty much a Platform/GameBoyMicro. And in the beginning, the mad scientist trio is playing a DS game similar to ''VideoGame/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 [[UsefulNotes/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"]], [[UsefulNotes/WorldWarII "I shall return"]] and [[UsefulNotes/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 [[VisualNovel/HigurashiWhenTheyCry Rena]] on the screen.
** In Episode 4.2 Eiko is teaching Ika to play [[VideoGame/{{Columns}} Sega's Columns]]. In the original manga version (Chapter 27) it's one of the VideoGame/{{Gradius}} games.
** [[spoiler:Chizuru]] intervening with the Nohmen Rider stageshow as a second Nohmen Rider mirrors the originally unplanned introduction of the second Franchise/KamenRider.
** Season 2, Episode 4.2: Ika and Eiko are seen playing VideoGame/VirtuaFighter on the off-colour [[UsefulNotes/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 ''VideoGame/StreetFighterIV'', as well as "[[VideoGame/SonicAndSegaAllStarsRacing Hedge]][[Franchise/SonicTheHedgehog hog]] [[VideoGame/MarioKart Kart.]]"
** In one episode, Ika Musume copies [[Anime/CodeGeass Lelouch's pose when using the geass]]. [[http://imgur.com/G3QbiB3 Here, have a look]].
** When Eiko's old Famicom buddy breaks down, she eventually replaces it in chapter 316 with a Nintendo Wii (Or rather, [[BlandNameProduct Will]]), and uses the Virtual Console to buy a crap-ton of retro games and binge play them. Among those games, one can recognize ''VideoGame/SuperMarioKart'' (Whose Battle mode Eiko and Ika are seen playing at the end of the chapter), ''VideoGame/KirbysAdventure'', ''VideoGame/SuperMarioWorld'' and ''VideoGame/{{Gradius}}''.
** In chapter 379, as she's leading Ika around, Keiko keeps saying map directions in her head, but is distracted by two kids reciting part of the Konami Code.
** In chapter 392, when Ika marks her territory around the Beach House (Accidentally recreating part of Nagisa's nightmare in the process), she does so with squid ink, a la ''Franchise/{{Splatoon}}''. This is no coincidence, as the corresponding manga volume's notes reveal that this scene was intentionally made in tune with the collaboration the manga had with ''VideoGame/Splatoon1''.
** In chapter 172, Eiko is distracted from her homework by Ika playing ''VideoGame/StreetFighterII''. And when she goes to Sanae's house, she gets distracted by Sanae's new [[BlandNameProduct Xwox]] [[Platform/XBox360 360]], and ends up playing ''VideoGame/KatamariDamacy''.
** In chapter 206, the Three Stooges are too busy playing ''VideoGame/SuperBomberman'' to care about Ika visiting their lab.
** In chapter 333, the beach house has a collab with Noh Men Rider. Chizuru is dressed as the Rider, Eiko is dressed as a villainess, and Squid Girl is dressed as herself since she already looks like a minion. When Chizuru confronts Eiko, Eiko elects to shove Squid Girl out to fight Chizuru while proclaiming, [[Franchise/PokeMon "I choose you, Tentacruel!"]]
** In chapter 358, Keiko has a ''Series/SeibuKeisatsu'' poster on her wall. She and Squid Girl watch the [=DVDs=] until the next morning. After getting a load of the explosive stunts, Squid Girl resolves not to make Keiko (and the rest of the police) her enemy.
* ShrinkingViolet: Ayumi is normally too shy to converse with people, only being able to do so when she wears one of her dad's kigurumi masks. The only people she's normally comfortable around are the one she sees as non-human, like Ika (although granted she technically ''is'' non-human), Sanae and Chizuru.
* 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: [[EveryoneHasStandards She doesn't.]]]]
* SingleTargetSexuality: Sanae with regard to Ika.
* SliceOfLife: Slice of Squiddly Life.
* {{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".
* SmugSnake: Ika is extremely overconfident and rude to pretty much everyone she meets, considering herself superior. While it bothers Eiko and Goro, nobody else seems to mind since she's so adorable. It's not uncommon for her to get knocked down a peg for her attitude or show genuine emotional connection to others while pretending to be smug.
* SnapBack: Chapter 231 ends with the beach house being blown up by an "anti-theft" device the Stooges created. It's fine in the next chapter.
* SneezeCut: In episode 11.3.
* SpaceWhaleAesop: Courtesy of Chapter 329, if your friend is starving herself to fit into clothing that's too small, just have the local kooky scientists use their expanding ray to make the clothing bigger.
* 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: the premise.
* {{Squee}}: 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:
** If Chizuru 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.
* StrandedInvader: The eponymous character came to the surface world to conquer it in revenge for humans polluting the ocean. However, due to a serious miscalculation in just how many humans there are, and what they're capable of, she hasn't got a chance at completing her invasion. Then she smashes the wall at the Lemon Beach Shack, and ends up having to work for the Aizawa sisters, Eiko and Chizuru, to pay off her debt. To make matters worse for Squid Girl, when she does try to take Eiko, and her little brother Takeru hostage, Chizuru demonstrates that she's a force to be reckoned with.
* 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.
* TemptingFate: Chapter 167 has Ika wear a hat to protect against the sun, but the Three Stooges' antics annoy her into wanting to remove it, thinking she doesn't need it. Cue a pellet of bird crap landing on her head, with Ika lampshading what terrible timing that was.
* 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. This time, Ika ''was'' just as scared as everyone else, to the point her lingering fears from that incident were the focus of another chapter.
* TheFriendsWhoNeverHang: As the manga reached 300-ish chapters and Anbe grasped for ideas, he started coming up with single chapters that mash together characters who've never really interacted with each other before.
** The Three Stooges and Mr. Tokita team up to build a better Ika bot.
** The Three Stooges recruit Sanae due to her ability to locate Ika at all times.
** The Three Stooges build a medical bot for Ruka.
** Goro's mom and Cindy bond over their love of alien investigation shows.
* 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).
* ThirdPartyPeacekeeper: In the Season 2 finale, Eiko and Squid Girl are fighting yet again. Only this time, it doesn't seem to be letting up. Chizuru announces that they'll be closing up early and heading to a local festival. She gets a bit of an assist from Kozue Tanabe (implied to be an Octopus Girl), who tells Eiko how to find Squid Girl after the group gets caught in a sudden downpour.
* ThroughHisStomach: Sanae attempts to win over Ika's heart a few times by cooking. Too bad for her, it never works because she's a LethalChef.
* 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 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: Anime-only; 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 breaks a window and (according to a post-chapter panel) travels back in time to the age of the dinosaurs.
* {{Tomboy}}:
** Nagisa the surfer chick.
** 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.
* TooKinkyToTorture: Sanae enjoys most of the abuse she gets from Ika's tentacles. Cindy doesn't mind being grabbed by them either, because she considers them fascinating.
* 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.
* TranquilFury: Chizuru never raises her voice when angry. She just lowers her voice a few octaves and opens her eyes, and everyone presents craps themselves.
* 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 unless you count the omake...
* UniversalGroupReaction: When Squid Girl learns about tickling, she has a field day tickling everyone in sight. Then she suggests trying to tickle Chizuru Aizawa. Eiko tries to warn her that tickling Chizuru, who hates being tickled, would be an all-out declaration of war. Squid Girl asks if they wouldn't all enjoy seeing Chizuru laughing "squid-sterically", to which Eiko, Sanea, and Cindy all think in unison "Yes. More than anything." [[spoiler: It doesn't go as planned, as Squid Girl can't find Chizuru's ticklish spot, but DOES acknowledge the declaration of war.]]
* TheUnreveal: One chapter reveals that wearing Ika's shoes is bad for a human, enough to make Ika briefly scared at the thought. Eiko, who did put them on out of curiosity, is naturally worried, but the chapter ends before Ika can reveal why, and the issue is never brought up again.
* UnusualEuphemism:
** The subtitles for the anime give Ika quite the potty mouth. However, all of her curses are squid puns (ala Franchise/TeenageMutantNinjaTurtles and turtle puns) so the show still remains relatively tame.
** Several male customers refer to Ayumi's [[BuxomBeautyStandard large assets]] as her having "romance".
* 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. Part of this comes from the fact that no matter how intense her goals are, or how dangerous she is in reality, she's very easy to make cry, easily manipulated by seafood as a prize, and comes up with plans such as intimidating the world because she has intense math skills. Furthermore, she's incredibly lazy about invading and prefers lounging around and playing videogames, a thing Eiko points out.
** 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?"
* WeightWoe: In chapter 329, after Kiyomi accidentally gets a pair of shoes that are too small, she starves herself just to fit into them.
* 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.
* WellIntentionedExtremist: Squid girl. Or at least she would be if she could stop herself from being sidetracked.
* WhatBeautifulEyes: As Chizuru has EyesAlwaysClosed, she counts for this trope when she's shown with them open without malicious intent.
* 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.
** Mr. Tokita is scared of dogs, even if they're harmless puppies. When his daughter brought one such adorable puppy home, he kicked himself out so as to not deal with it. Eiko manages to convince him to try and get over it.
* 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 a long time 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?"
* YouAreBetterThanYouThinkYouAre: The focus of chapter 402, in which Ika and the others try to boost Kiyomi's self-esteem by praising her. Unfortunately, it just made her extra shy and embarrassed as she's bad at taking compliments.
----