In episode 1 of the second anime, Nyarko taunts the Nightgaunt she's beating up by quoting Kintaros from Kamen Rider Den-O ("You won't be able to beat me just by acting tough!"); Kintaros' voice actor, Masaki Terasoma, is the narrator in this episode.
Nodens, a recurring character, is voiced by Bin Shimada; the show's staff really seems to get a kick out of having him quote Paptimus Scirocco (and then have him act like a total goof.)
After Nodens delivers one such quote, Yoriko remarks "The way he said it, you'd almost believe he came from Jupiter!" Which of course, Scirocco did.
Nyarko-San W episode 9 features a few prominent quotes from Crossbone Gundam; Agent Smith, the villain of that episode, is voiced by Kouji Tsujitani, who also plays Crossbone's Older and Wiser mentor character Kincaid Naunote Better known as Seabook Arno, protagonist of Gundam F91].
Adam and Eve Plot: Invoked in episode 7 of season 2. Mahiro wakes up on what appears to be a deserted island with Nyarko, and she immediately mentions this trope to him. However, in actuality, they're still at the indoor swimming park, and several people walk by when he mentions it, and the camera also changes angles, revealing the shops on the other side of the two.
What makes it even funnier? Those buildings are a prime example of Behind the Black — unseen by the audience until the angle change, but right smack-dab in front of Mahiro. Didn't really think that one through, did you Nyarko?
Aliens AreInsane: Nyarko and Kuko are psychotic stalkers, and the Great Old Ones are so obsessed with Earth pop culture that they have smuggling of it, and some of their media watchdogs try to destroy the Earth over considering it a threat to moral health. And people say Humanity Is Insane.
The aliens are based on the Cthulhu Mythos. Nothing else needs to be said about this.
The show also cheerfully skewers the Harem genre; while Mahiro has three Pretty Freeloaders, one is interested in another, while the third is a guy.
A.I. Is a Crapshoot: A first it looks like it's this for the Banshin and then it looks like it gets subverted because they simply based it's mind on Nyarko's and then it turns out that it really is crazy enough to kill Mahiro after all.
Alien Lunch: An ongoing Running Gag. Nyarko keeps using alien ingredients on everything she cooks, be it shantak bird eggs, Shub-Niggurath (the "Black Goat of the Woods") meat or her famous "BLT" (Byakhee-Lloigor-Tsathougga) sandwich. And then there's the hotdog from Episode 4 of the second anime — "dog" here meaning "Hound of Tindalos".
Mahiro: "I'm definitely gonna kick the crap out of you if you prepare something like that!" (Episode 1, referring to the "BLT")
All Love Is Unrequited: Almost all the relationships in the series. Hasta and Tamao (and later Cuuko) have feelings for Mahiro, Luhy develops feelings for Hasta, Cuune has feelings for Cuuko... And of course, the series centers around Nyarko's feelings for Mahiro, but he actually does like her even if he's not willing to say so out loud, a situation that slowly improves.
All There in the Manual: One can watch the anime without reading the novels, but it does provide a lot of useful information. For example, after busting up Nodens' black market auction, Nyarko took 300 years' worth of paid vacation in order to be with Mahiro, and Mahiro is revealed to be able to perceive and resist fluctuations in space-time (which is mentioned early on, but becomes a Chekhov's Skill later).
Analogy Backfire: In episode 7 of the second TV series, Nyarko compares herself and Mahiro to two trees which have grown together; he responds that diseased limbs need to be removed immediately.
Anguished Declaration of Love: Nyarko does it to Mahiro in episode 6 of season 2, after being extremely unhappy watching his fake date with Kuuko. She lays on top of him in his bed, and tells him yet again that she cares for him deeply, and wants to know what his feelings towards her are, as she's unsure of them.
Animation Bump: Remember my Love(craft-sensei) is a Flash series, but the Ending credits are done traditionally. As a result, the Credits have better animation than the show itself.
Art Evolution: Comparing the character designs from Remember my Love(craft-sensei)'s ending to the two TV shows an interesting reversal. In the former, Mahiro's face was more lean and angular (and therefore looked slightly older and more masculine), while Nyarko's was rounder (and therefore younger-looking and more feminine); in the latter, these traits have swapped, so Nyarko's face is more angular while Mahiro's is rounder.
Artistic License - Physics: Cuuko claims that her cousin Kunne's flames can reach a "thousand degrees", and that her chill attack could reach below one thousand degrees note this would be well below Absolute Zero. Mahiro responds that it sounds like something a kid would think up.
Mahiro:"Don't ignore the laws of physics."
Ascended Extra: Shantak was a minor character in the 2012 series, but got a pretty important role in the sequel.
Aside Comment: Nyarko looks at the camera and repeats a second time that she has a convenient barrier to keep up The Masquerade because, in her own words, it is important information.
Attempted Rape/Black Comedy Rape: Twice. In episode 2 (second anime) Kuuko defeats Nyarko in battle and then ties her down on a four-poster bed. At the end of Episode 6 Nyarko tries to get Mahiro in his bed. In both cases the attacker believes it to be an act of love, and the victim succeeds in fighting them off.
Babies Make Everything Better: In episode 7 of the second anime, Yoriko says she approves of Nyarko dating Mahiro, but asks her to slow things down, since "high schoolers should have a high school romance". Nyarko agrees, but thinks to herself that parents always change their minds when the grandchildren start being born...and develops a HigurashiSlasher Smile that creeps Mahiro right the hell out.
Bad Boss: According to Nyarko, her boss is unreasonable and sleeps all the time, and if you disturb his naps he gets mad enough to destroy the universe. Yup, he's Azathoth.
The Beard: In episode 5 of season 2 (W), Kuuko claims to be Mahiro's fiance in order to thwart her cousin Kuune's advances and avoid a marriage interview. The later doesn't seem too convinced at first, so Kuuko asks the other characters to play along, and bribes Nyarko into doing so by giving her the contract Mahiro wrote (while trapped in Nyarko's body) in the first episode.
Be Careful What You Wish For: Mahiro in episode 11 moans that he wish he could have peace and quiet. Then in episode 12, he gets it, and ends up being the last man on Earth, and he starts to realize how important his friends and family really are to him.
BFS: Nyarko's crowbar turns into one in episode 12.
Beehive Barrier: In Episode 10, Nyarko (in her own body again) summons one to block an energy blast from the leader of the rogue Yithians.
Cuuko: "The magic circle effects were difficult. We're using them now while we still have room in the budget."
The first part of this episode combines this with Info Dump as Nyarko addresses the audience directly to get new viewers up to speed, for example giving little introductions for Yoichi and Tamao when the group gets to school.
Buffy Speak: When asked about the crowbar she was holding, Nyarko describes it as "some kind of unspeakable bar thing."
But Thou Must: Spoofed in Nyaruani episode 5, "RPG", where Nyarko describes the big popular RPG in space. Sometimes the monsters you defeat will want to join your party; your choices are "Yes" or "Yeah". And then they demand payment or refuse to help you.
Cain and Abel: Nyarko's older brother Nyar-o ran away from home because he's Book Dumb while Nyarko is a Child Prodigy (she was a topnotcher at a prestigious university, while he had to drop out of a C-list college). He blames her for his downfall (because she hit his head while playing space gateball) and tries to antagonize her after he gains his own Full Force Form — so he wanted to be.
Catapult Nightmare: Episode 9 opens with Mahiro having one...but, because it's Mahiro, the "nightmare" is the Dating Sim ending of the previous episode altered so that he says "I love you" to Nyarko and kisses her willingly instead of being Tsundere as usual.
Call Back: In Episode 11, Nyarko uses the Mirror of Nitocris to suck back the Shaggai hornets she intended to eat as barbecue at Mahiro's request. Then Mahiro remembers that it was the same mirror with which Nyarko let him realize that they have switched bodies. Naturally, he's not too thrilled about the implications as to what it could have done to him.
Calling Your Attacks: Isurugi and Isuka do this in episode 10. After a while Mahiro questions if they're grade school kids.
Calvinball: Space CQC is explicitly stated to be whatever one claims it to be. Even if their opponent disagrees.
The Cameo: Characters from other light novel series, such as Miyamasanchi no Berutein (written by Aisora) and Rl'yeh High School (illustrated by Koin) can often be seen in the background, with the two main girls from the latter actually appearing as Mahiro's classmates. In turn, Mahiro, Nyarko and Yoriko appeared as minor characters in the former.
Anime: Guthatan and Roy Fogger from the first season, Tsuruko and the Dreamlands gods from W.
Can't Stand Them, Can't Live Without Them: Basically sums up Mahiro's relationship with Nyarko, Cuuko and Hasta. No matter how often their personalities (and preferences) clash, it's obvious that all four of them need each other. He learns this lesson at the end of the first season when he's sent to a completely empty world; the second season has a similar situation, where the trio are being recalled by their bosses, but Mahiro's main conflict is the fact that he's powerless to stop it.
The "protective charm" Nyarko gives Mahiro from Episode 2note Which Lovecraft fans will recognize as the Shining Trapezohedron comes back in Episode 10 to play Pocket Protector and save Nyarko-in-Mahiro's-Body. It returns again in episode 10 of Season 2, when Mahiro summons a sick Nyarko in a particularly nasty foreshadowing/subversion loop (ultimately subverted; Nyarko can't fight in her state, and the Yuggoths are vaccinated against her sickness). It still has the potential to boomerang back, since its primary purpose is to let Mahiro summon Nyarko in times of great need.
The Mirror of Nitocris also becomes this when, in Episode 12, Mahiro uses it to suck in a Nightgaunt, and was eventually used by Nyarko to move him out of the alternative dimension he is trapped in.
Cuuko doesn't like that Nyarko is always swooning over Mahiro.
Nyarko doesn't like Hasta too much when the latter seems a bit too friendly with Mahiro. Cuuko's attempts to hook them up only makes things worse, particularly as Hasta doesn't seem to mind it.
In episode 5 of season 2, Kuuko pretends that Mahiro is her fiance to thwart her cousin Kuune's advances. Although she promises to give Nyarko the contract Mahiro wrote in the first season (while trapped in Nyarko's body), Nyarko is clearly uncomfortable with the plan, and shatters her tea cup after watching Kuuko clinging onto his arm. She also becomes unhappy at the fake date Kuuko goes on with him in the next episode.
Kuune, Kuuko's cousin, also exhibits this trope in episode 6 of season 2, and tries to thwart their plans from time to time during the fake date.
Color-Coded Characters: Human characters can be distinguished by their natural hair color; the Lovecraftian characters have bright color motifs based on their Mythos counterparts. Hasta is yellow (alluding to Hastur's title, the "King In Yellow"), Luuhi is green since she is Cthulhu, and Cuuko is red — alluding to Cthugha, a sentient fireball. The odd one out is Nyarko, whose hair and Henshin Hero form is silver. Nyarlathotep's traditional color is black, though it is used for her standard outfit.
In Remember my Love(craft-sensei), Ato-ko's color motif is black, appropriate for a Yamato Nadeshiko.
Nyarko also has had these moments twice. The first is in Episode 4 when she misunderstood Yoriko's advice to her to start her relationship with Mahiro as Just Friends for being friendzoned before Giving Up the Ghost. The second is in Episode 7 (coupled with Heroic BSOD) after Mahiro bluntly tells her that he doesn't like her. She goes into it again later in the episode to guilt trip him into doing things with her, but he draws the line when she tries to drag him into a sex museum.
Cuuko and Hasta simultaneously in Episode 10 after Nyarko (in Mahiro's body) gives Mahiro (in Nyarko's body) a really deep French kiss. They remain that way during the entire climax.
Kuune, Kuuko's older cousin, does this when the former mentions she's getting engaged to Mahiro. It must have been shocking, as Kuune is still whited out a few scenes later.
Conflict Ball: The trio's reactions to Guthatan in episode 11 fringe on this, Nyarko especially. While Mahiro is trying to look after this child who was put in his care, the trio acts even more selfish and disruptive than normal, with Cuuko is needling Mahiro about breakfast while Nyarko and Hasta get insanely jealous of the attention he's giving Guthatan. Probably the worst of it is when Nyarko notices that Guthatan's hair is wet and she's in new clothingnote Mahiro had to bathe her after she got her clothes dirty in the kitchen and jumps to the conclusion that Mahiro had sex with the underage alien girl. You can kind of understand his anger at that point.
Conservation of Detail: The main characters muse that Yoichi must be possessed by a Yithian because he hasn't come to school. When they go check on him, they turn out to be absolutely correct.
Mahiro keeps a fork in his pocket, for whenever Nyarko is going wild over him.
Isurugi, the renegade Yithian, prepared a Space CQC Jammer to combat Nyarko. Isuka, the Yithian on Nyarko's side, prepared a Space CQC Jammer Canceler. Countered by a Space CQC Jammer Canceler Breaker, then by Space CQC Jammer Canceler Breaker Eraser... and so on and so forth. Even though Isurugi eventually wins out, things still do not go according to plan.
Creator Cameo: That little ghostly devilfish that sometimes appears in monstrous crowds or flying quickly across the screen is Aisora's avatar.
Credits Running Sequence: Mahiro does a brief one running in place with a giant Nyarko and Earth in the background in the opening for W (season 2). He also does one where he's running away from Nyarko, Kuuko, and Hasuta.
Nyarko, energetic she may be, frequently breaks down into a tearful mess for whenever Mahiro gives her the cold shoulder (or, depending on circumstances, the fork).
The only time Cuuko becomes tearful is whenever she misses the Xoth-731, a game console she loved so much. It also doesn't help that she had to reluctantly terminate it after it brainwashed a bunch of Deep Ones with a Zombie Apocalypse game.
In Episode 7, poor Hasta (voiced by Rie Kugimiya, no less) storms off the cafeteria crying when he thought Nyarko is pregnant with Mahiro's child, despite the latter's insistent (and truthful) denial.
Finally, in Episode 10, Mahiro himself (albeit in Nyarko's body) sheds Tears of Remorse when he thought Nyarko (in his own body) died shielding him from the Star Child Guardian's beam attack, lamenting that he should've been nice to her, who's always been more than willing to risk life and limb for his sake. Of course, she's alive (the black crystal Nyarko gave to him back in Episode 2 certainly saw to that), but only played dead to have him come close to her and receive a really deep French kiss.
Curbstomp Battle: Well, this is what happens when you pit mere monsters against the Crawling Chaos.
Damned by Faint Praise: In episode 7, Mahiro attempts to apologize to Nyarko for saying he didn't like her, but the best he can manage is to say that he likes her better than certain foods (which, as Tamao points out, nobody likes). But it's good enough for Nyarko.
Dancing Theme: A brief one in W's (season 2) opening by various characters.
Date Crêpe: Mahiro and Kuuko order some in episode 6 of season 2. When Kuuko tries to take a bite out of his crepe, her cousin Kuune shows up from behind the bushes and eats the entire thing in one bite. So she shares her crepe with him, and when he takes a bite out of it, Kuune becomes extremely upset.
Date Peepers: Kuune, Nyarko, Hasuta, Shantak, and Mahiro's mom all follow him and Kuuko on their date in episode 6 of season 2. Then it turns into more of a group outing while at the restaurant as they all join the two for lunch.
A Date with Rosie Palms: When Nyarko accidentally switched bodies with Mahiro in Episode 9, she spends an inordinarily long time in the restroom, then comes out radiantly singing "Oh, boys are so great... It's a feeling that girls just won't understand..." Naturally, Mahiro is livid about this.
In episode 7, we see Cuuko apparently stayed up all night waiting for Nyarko (who lied in order to get her out of the way), and slept through breakfast while having some...entertaining dreams. Later, when Mahiro asks her why she missed breakfast, Cuuko said she was waiting for Nyarko but "somehow ended up satisfying [herself]". Wisely, Mahiro decides not to ask any further questions.
In Episode 2 of Season 2, Kuuko is shown groping herself while reading out loud from a book that, if not explicitly sexual, certainly sounds suggestive.
Dating Sim: Lovecraft Plus, mentioned in the fourth episode of the short Flash, is an inverted version of the standard dating sim that happens to have SANamong its stats. Instead of getting the girls to fall for you, the girls try to get you to fall for them Your SAN points are basically your resistance to the YandereStalker with a Crush's advances. Lose enough SAN and you end up with her forever, wallowing in your mutual insanity. Definitely a game worthy of the title.
This is also the premise of Episode 8. The characters are stuck in Doki Doki High School until Mahiro scores with either Nyarko, Cuuko, Hasta or Tamao.
Deserted Island: In episode 7 of season 2, Nyarko tells Mahiro that they're both stranded on a deserted island after he awakens from having fallen in the water. However, as soon as he points out they're still inside the swimming park, several people walk by, and the camera changes angles to show the shops on the other side of where they are.
Did You Just Groin AttackCthulhu?: A Nightgaunt, actually. A subversion, since Nyarko's an Outer God, in the form of a schoolgirl. Played straight with Mahiro who frequently threatens Nyarko with a fork.
Disney Dog Fight: Nyaruani episode "Loyalty" has Nyarko getting jealous over how much Shanta-kun seems to like Mahiro; he responds by suggesting they do this. Shanta ends up choosing Nyarko...after some percussive persuasion.
Disproportionate Retribution: In episode 10, the Yith, or at least an extremist, space Moral Guardian cult of them, wish to destroy Earth because they're corrupting morals of space aliens with Earth's entertainment.
Ghutatan's butler in episode 12 wants to get rid of Mahiro because the latter made it hard for him to get his hands on Eroge.
In the light novels, Nyarko and Cuuko used to beat up their grade-school classmate Nyogta for bullying Hasta; as an adult, he gets his revenge by erasing the girls from existence.
Distracted by the Sexy: Nyarko uses this against Cuuko in episode 6 by throwing out some pictures and claiming pictures of her in a swimsuit flew out. This distracts Cuuko long enough for Nyarko to hit her with a finishing blow. Said pictures were actually of Mahiro taken from various angles.
"Do It Yourself" Theme Tune: Kana Asumi [Nyarko] sings the themes of all three adaptations — solo on the first Flash opening ("Like, Like, Love") and the anime ending ("Always Be With You"), collaborative on the second Flash ending ("Catharsis of a Woman's Love", with Azusa Kataoka [Atko] and Sayuri Hara [Nyarue]) and the anime opening ("The Sun Says 'Burn, Chaos'" with Miyu Matsuki [Cuuko] and Yuka Ootsubo [Tamao]).
Don't Explain the Joke: In episode 5 of the first TV series, Mahiro chasizes Nyarko for having to spell out the pun behind the Xoth game console's name.
Dope Slap: Mahiro on Nyarko many, many times. In episode 2 of Nyarko-San W, he takes a page from Akiko Narumi's playbook and uses a green slipper.
Double Entendre: Believe it or not, Hasta uses the crap out of this. Most of the time he uses the term "gattai"note "Combine," frequently used for Combining Mecha to refer to doing it; this is not a corruption as the term can mean such an act. However, all bets are off when he refers to it as "FinalFusion."
A gender-based one, in Episode 7 Mahiro made it very clear to Nyarko that he wasn't interested in her and she finally took it seriously. So how did everyone respond? By pressuring Mahiro to take her out on a date. Admittedly Nyarko was shocked and saddened when Mahiro told her, but if the genders had been reversed the scene would have been considered very creepy.
Double Standard: Rape, Female on Male: Not outright rape, but Nyarko's repeated attempts to seduce Mahiro (presumably in the hopes that he'll get into it) are treated as comedy, when the same acts committed by a man on a woman would most certainly not. It might have something to do with the fact that you know Nyarko will never succeed, thanks to Mahiro's skill with forks.
Family-Friendly Firearms: The "guns" Isuka and Isurugi use in episodes nine and ten resemble old handheld cameras, or radar guns. The characters still react to them as real guns however, such as when Isurugi, while inhabiting Yoichi's body, points the gun at his own head.
The camera appearance is based on the description of Yithian weapons from The Shadow Out of Time, which could be quite deadly.
Fanservice: The Light Novels are illustrated by the artist who did Kanokon's, so one should expect it. Invoked in the first TV episode with Nyarko telling Mahiro that since this is an anime adaptation, their fans surely want to see them get wet. Mahiro flatly rejects it, claiming that he doesn't care about that kind of fan.
Fast-Forward Gag: In the first episode of the second anime series, Nyarko's explanation for who/what she is and her purpose for being on Earth gets fast-forwarded due to being extremely long-winded and Mahiro has to summarize everything in a format that the audience can understand and respects broadcasting time constraints.
Even funnier, if you slow down that sequence to half speed, you can understand Nyarko's dialog; it's an almost direct quote from the original light novel where she (indirectly) reveals that her boss is Azathoth.
Feuding Families: As a race, the Nyarlothotepians and Cthuguans are mortal enemies, with Cuuko's crush on Nyarko being a case of If It's You, It's Okay. When Cuune shows up, Nyarko explains to Mahiro that the shame and dishonor that would result if the crush became public would probably destroy Cuuko's family.
Fictional Geneva Conventions: In the "Cooking" segment of Nyarani, Nyarko mentions difficultly of getting an "ingredient" due to the Space Washington Treaty.
Fighting a Shadow: Conversed in episode 1 of the second season, as Mahiro and Nyarko talk about their compatibility issues. Mahiro points out that Nyarko (as a beautiful human girl) is not her true form. However, Nyarko counters that her human form is just one of her Thousand masks, so it's just as real as can be.
Mahiro: "I'm scared to see the remaining 999."
Flashback Echo: In a few episodes, Mahiro blushes and gets really flustered whenever he gets a good look at Nyarko's lips — because he's remembering the two times they've actually kissed so far.
This gets invoked again in episode 9 of season 2 regarding the vacuum cleaner Mahiro's mom is using throughout the episode, as well as events that happened in an earlier episode with Kuune. Both Mahiro and Nyarko comment on said vacuum, which did nothing in particular aside from screaming "Cyclone!"
It comes into play again during episode 10 of season 2. The latest alien threat seems ready for anything Mahiro, Kuuko, and Hasuta can throw at him, and then they all fail for one reason or another. Then Nyarko's phone begins to ring, and its the music from it that causes them to die. Mahiro immediately points out that it wasn't much of a foreshadowing clue.
Mahiro's actually gotten to the point where he's actively trying to find the foreshadowing in every plot arc. He always chooses whatever he thinks would result in the dumbest, most nonsensical ending, and while he's right in that regard, he still tends to be wrong because something always comes out of nowhere that's even dumber than what he suspected.
Fork Fencing: Mahiro and his mom use forks to keep Nyarko, Kuuko, and Hasuta in line when they act out. Despite having weaponry that's literally out of this world, the forks seem to be the most feared thing to them anytime he pops one out.
In episode 3 of Nyarko-San W, Mahiro gets so annoyed with the combined Zhar/Lloigar to start flinging forks; he starts screaming in pain, and Nyarko says that "for some reason", Mahiro's forks hurt a lot.
A Form You Are Comfortable With: Mahiro tells Nyarko he pictured Nyarlathotep far more monstrous. She offers to show him some of her other forms... if he doesn't mind losing his sanity. Mahiro passes. Cue a shot of twenty SAN Points getting dashed off of a Call of Cthulhu character sheet.
Fourth Wall Mail Slot: Spoofed in episode 5 of Nyaruani, where Mahiro and Nyarko answer fans' questions about the series. The first question is about a Series Continuity Errornote "Why is lunch after third period in the first light novel, but after fourth period in the GA Magazine short?" which annoys Nyarko so much that she rips up the postcard and ends the segment there...but still says "To Be Continued" afterwards.
Freeze-Frame Bonus: In episode 8 of the second season (the Trapped in TV LandDating Sim episode), Nyarko's Christmas present to Mahiro is a marriage registration. Reading it reveals a lot of amusing details; for example, Nyarko's birthday is April 15, 2009 (the day the first light novel was released), her parents are Father of the Million Favoured Ones and the Bloated Woman (two of Nyarlathotep's other forms), and one of the marriage witnesses is Harvey Walters, the sample character in the 5th edition of Call of Cthulhu.
In the Nyaruani episode "RPG", Nyarko's description of the game is accompanied by mental images of the game; the monsters who ask to join are iTunes, Quicktime, and Bonjour (as in, the program icons with little eyes drawn on).
Gag Series: The Flash series focused on surreal humor more than any plot. The TV series probably falls halfway between this and Excuse Plot.
Gainaxing: Kuune does this when she's walking slowly towards Mahiro and Nyarko in episode 9 of season 2.
Gender Flip: Nyarko, Cuuko, and Luuhi. In the Mythos, Nyarlathotep's human forms tend to be male, and Cthugha and Cthulhu are considered "male".
On the meta side, Atlach-Nacha was originally described as male, though later writers turned "him" into a female.
Another, anime-related meta example: Mahiro is tsundere, helpless against monsters, but has no problem with hitting Nyarko; Nyarko is bold, hyperactive, and is easily beaten by Mahiro despite being powerful fighter. In other words, they're the gender-flipped version of the standard anime couple.
Glamour Failure: Humanoid Nyarlathotepians can be distinguished from regular humans (and other anthropomorphized Lovecraftians) by their silver hair and huge cowlick, most prominent of which are Nyarko, Nyar-o and Nyarue.
Godiva Hair: Nyarko sports this pretty much any time she's nude; they even make it so her hair magically falls in the right place to cover her butt in episode 1.
Grand Theft Me: Focus in the third Light Novel volume. One such Yithian, Isuka explains to Nyarko that her more aggressive kin are trying to pull this off on humanity in order to learn more of their entertainment. In an attempt to take over Nyarko (ostensibly to be able to fend off her more aggressive kin), she ended up causing Nyarko and Mahiro to switch bodies.
"Groundhog Day" Loop: Episode 11 ends with Mahiro trapped inside one, waking up once more on the Sunday he chewed out Nyarko, Cuuko and Hasta for being too violent while dealing with a bunch of Shoggoths, accidentally wounding their guest, Ghutatan, in the process. Then it was revealed that Lloigor, Ghutatan's butler, planned it all along to remove him, the last obstacle to gaining every eroge in the world.
Gut Feeling: In episode 3, Nyarko says "I have a bad feeling about this..." (and Mahiro agrees) when Tamao says a new student is joining their class: a cool girl with fiery twintails and A-cup breasts. Of course, it turns out to be Cuuko. By episode 5, they've gotten even savvier, and have the same exchange when Hasta leaves; sure enough, he turns up at school the very next day, prompting both to mutter "I Knew It..."
Ham-to-Ham Combat: Isurugi and Isuka have one when they constantly try to cancel each others field.
Cuuko, obviously. It took Mahiro playing around her Psycho Lesbian crush on Nyarko to convince her to let go of him and even win her over as a mutual ally by (purportedly) helping her get Nyarko.
Luhy has bounced back from her Villainous Breakdown when she was laid off by Cthulhu Corp. and has since taken many jobs, ranging from a takoyaki vendor to a Magical Girl at a stage play (with Nodens, who also seemingly pulled this off as a Kaiju), and later a teacher at Boryo High.
Played straight in episode 6 of season 2, when Nyarko becomes extremely upset at the fake date between Kuuko and Mahiro. After she complains about it, he tells her she should just go home if she's not comfortable seeing their playacting in order to fool Kuuko's cousin Kuune. Nyarko becomes downcast for the rest of the day and evening, and ambushes him in his room later that night with an Anguished Declaration of Love.
Nyarko suffers another one during the first half of episode 12 in season 2, after learning that her, Kuuko, and Hasuta's job of guarding Earth was done since they got the guardian for Earth done way ahead of schedule (it was supposed to take about 500 years to complete, but they managed to do it overnight). She is also told that staying on Earth any longer would be considered a crime, and Mahiro tells her he can't do anything about it either. She snaps out of it the instant she hears that they want to field test the new guardian, with the intention of destroying it so as to be allowed to stay on Earth while her superiors have to build a new guardian.
In season 2, when Cuuko kisses Mahiro on the cheek (which is considered a major love ritual by her race), Cuune flips out, quotes the Big Bad of Mobile Suit Crossbone Gundam ("Burning...the Earth is burning...") and flies off while laughing maniacally.
High-Pressure Blood: Mahiro's fork-stabbings make Nyarko gush blood in the light novels and Nyaruani shorts; in the TV series the worst they do is little lumps on the head.
High-Pressure Emotion: Cuuko's full body blushing is actually harmful. Justified, considering she is a living fireball.
Nyarko: "Stop hugging me! You wanna burn me to death or what?!"
Episode 12 of the second TV series contains several direct homages to the second Urusei Yatsura movie, which was also about people being transported into a world with no other humans, as well as an apparent "Groundhog Day" Loop. This includes several shot-for-shot recreations of the latter, including the Red Herring scene of Guthatan sitting nearby a bank of pay phones which ring as Mahiro attempts to call Nyarko.
In the second episode of the second anime, Nyarko complains that Cuuko's lasers shouldn't be considered close-quarters-combat. At the beginning of the episode, Mahiro raised the same point about her using hand grenades.
Many of Nyarko's frequent insults towards Cuuko revolve around her hobbies, like gaming... In the first episode she was drooling over an anime/manga store's entire stock, including the games.
Nyarko's entire relationship with Cuuko is almost exactly the same as the one Mahiro has with her: an entirely unwanted admirer with extreme Perverse Sexual Lust who wants to make babies. Often, she'll even hit Cuuko with the same insults that Mahiro threw her way just minutes before (which Mahiro will Lampshade).
Iconic Logo: The Yellow Sign can be seen in several places related to Hasta (particularly the first TV series' opening). The Elder Sign can also be seen occasionally.
Idiot Hair: All Nyarlathotepians have one, pretty much a replacement of tentacles.
If It's You, It's Okay: Even if it's actually Mahiro in Nyarko's body, Cuuko would still attempt to have her way with him, so long as it's Nyarko's body. The fact that Mahiro is relatively easy on her compared to Nyarko also helps.
Cuuko: "Just her [i.e, Nyarko] body will do."
Kuuko gives Mahiro a kiss to thwart her cousin off in episode 9 of season 2. He later asks if that was okay, since Kuune said that particular kiss was an important love ritual. She says that she didn't mind doing it because it was him.
Laser-Guided Amnesia: At the end of the Trapped in TV Land episode, it seems the only person who remembers anything is Mahiro. It's implied that Nyarko does as well, since she was looking at him and smiling a lot, but refused to say why when he asks.
Lightning Glare: Nyarko and Kuuko do this to each other when they both spot the last copy of a limited edition game in episode 8 of season 2.
Long Title: The title of Remember my Love(craft-sensei) episode 9 is *deep breath* "How Mahiro Came to Love the Girl Despite Being a Normal High Schooler Who Cannot Even Sense in the Slightest That the Universe Is at Risk of Destruction, and Suppresses a Vague Worry That Tomorrow the Sun May Not Rise from the Same Direction or at the Same Speed or Even Shine at the Same Luminance and Follow the Same Orbit".
Loophole Abuse: In episode 12 of season 2, Nyarko is told that her superiors finished building Earth's new guardian way ahead of schedule, finishing it overnight instead of taking the estimated 500 years to complete. As a result, she, along with Kuuko and Hasuta, are ordered to return to space, and Mahiro says he's just an Ordinary High-School Student, so he can't do anything to help them. As they tour the area where the guardian was built, Nyarko overhears her superiors mentioning a field test for the guardian to ensure its working correctly. She, along with Kuuko and Hasuta, instantly decide to volunteer for it, reasoning that if they could defeat the guardian, it wouldn't be able to actually guard Earth. In reality, the three just wanted an excuse to bash the thing so they could then stay with Mahiro longer.
Love Potion: In episode 11 of Nyarko-San W, Nyarko's friend Atoko sends a box of chocolates which she shares with everyone (except Mahiro, who refuses). A short while later, everybody seems to have hiccups, and the next thing you know Mahiro is being pursued by everyone except Nyarko, who's herself trying to escape from an obsessed Luhy. One phone call later, Nyarko learns that there was a love potion in the chocolates which makes you fall for whomever spoke to you after you hiccuped, but thankfully only lasts an hour. Nyarko insists that she didn't know about it, or else she wouldn't have shared the candy with everyone; besides, she wants to win Mahiro's love legitimately. When asked why she wasn't affected, she suggests that her love for him is stronger than anything the potion could have caused.
It also affects Yoichi at the end, who was left behind and fishing the entire time Mahiro was being chased. Tsuruko also pops out, having caused a lot of the stuff that happened in the haunted house earlier. He sees her passing by, and then hiccups...
Nyarko didn't have those reservations in the first Remember my Love(craft-sensei) short, where she attempted to serve Mahiro a breakfast which was apparently laced with aphrodisiacs (judging by the fact that Shanta-kun snuck a sausage off the plate and ended up rolling around in ecstacy).
Luminescent Blush: This very obvious blush is proof that Mahiro isn't that annoyed by Nyarko's presence. Sometimes.
Ma'am Shock: In episode 11, as Mahiro and Guthatan are being chased by Nyarko et al, they pass by Luhy's takoyaki stand. Mahiro asks her not to say anything, but since Guthatan called her "obaa-chan" (a Japanese term of address for older women, such as grandmothers), she immediately rats them out when Nyarko comes by.
In the OVA, Nyarko refers to Luhy as a "30-year-old mage"note A meme on Japanese message boards that says if you're unmarried by age 30 you can become a magic-user; this pisses Luhy off enough that she starts freezing over the living room.
Madness Mantra/Survival Mantra: After losing his SAN, Mahiro begins to repeat "It's only ink..." while trying to forget about the pool of Nightgaunt blood shed by Nyarko.
Subverted with the pan up Nyarko's legs to her face in the opening, as it's not a male looking, but the very female Cuuko.
Man, I Feel Like a Woman : Inverted and played straight. When Nyarko and Mahiro switched bodies, Nyarko wasted no time at all and comes back from a LONG trip to the restroom happily singing "Oh, boys are so great!! It's a feeling that girls just won't understand!!". On the flip side, Mahiro can't even find the courage to look at Nyarko's naked body while taking a bath.
Manic Pixie Dream Girl: Nyarko's entire personality basically both purposely plays up and spoofs this character type. She literally drags around Mahiro, and despite all his resistance he does find her cute.
Spoofed in the first episode of Nyarko-San W, where he interrupts the Bewitched opening parody, only for it to be revealed as a video project Cuuko is putting together for Nyarko. Strangely, he doesn't seem to notice that the title card for himself also mentions some woman named Eri Kitamura...
Mr. Seahorse: Invoked by Cuuko when she eventually makes the switchover from Psycho Lesbian lusting after Nyarko to Depraved Bisexual who wants Nyarko and Mahiro as her wife and husband; she declares that her new end goal is to become pregnant with Nyarko's child... and to make Mahiro pregnant with her child. Mahiro flips out at the idea, likely because, given who's talking, she probably could get him pregnant if she wanted.
Moe Anthropomorphism: The Great Old Ones depicted as teen girls (as well as one hot adult woman and an effeminate boy).
Moe Stare: Ear to ear smile, abnormally huge eyes... no doubt, she is the Crawling Chaos.
Monster Roommate: To protect Mahiro "from good morning to good night" Nyarko moves to his house. Not to mention the other cosmic nightmares that board at Mahiro's.
Mundane Utility: In the first anime series, Cuuko summons Aphoom-Zhah, the Cold Flame: a bright grey living flame that freezes on contact. Cuuko uses it to cool down a dessert.
Mundangerous: Mahiro's fork. In one episode Nyarko even remarks that "For some reason, Mahiro's forks hurt a LOT..."
Mahironote said while threatening Nyarko, Hasta and Cthuko: Do not underestimate the fork.
Mahiro: The fork... is the strongest weapon in the universe.
Episode 4 of Nyarko-San W reveals that Mahiro specifically sharpens his forks for the purpose.
Mystery Meat: Mahiro never got to know what was the "chicken" in the boxed lunch, let alone Luhy's takoyaki.
Never Say "Die": Inverted? In episode 7 of season 2, Kuuko and Nyarko talk about how the former's cousin, Kuune is dead. Mahiro immediately corrects them, saying she's merely trapped in another dimension, and a short scene from episode 6 showing Nyarko destroying the room changing device to also show she's not dead. They then settle for her being lost somewhere. The very end of episode 8 shows that she managed to escape, in a style parodying The Ring.
Never Trust a Trailer: In the tenth episode of the second season the preview makes it look like episode eleven will focus on Tamao confessing to Mahiro. While she does, it's under the influence of a love potion and is relevant for less than a minute.
Nice Job Breaking It, Hero: When Kuune reappears in episode 9 of season 2, she at first seems uninterested in what's going on right next to her while playing a video game. Namely that Nyarko is acting all lovey-dovey towards Mahiro. Due to the commotion they make, suddenly Kuune does indeed start looking at what those two are doing, and wondering if Mahiro was just pretending to be Kuuko's fiance to throw her off. Kuuko then does a kiss on his cheek, which shocks everyone around them, and Kuune is shocked that this particular kiss amongst their kind signifies a ritual of love.
Nice Job Fixing It, Villain: While they're not bad guys per se, Nyarko's superiors rebuild Earth's guardian in episode 12 of season 2, which means Nyarko, Kuuko, and Hasuta are no longer needed to guard the planet. They also upgrade it, and in initial field testing against Nyarko, Kuuko, and Hasuta, their attacks do nothing against it. Unfortunately, for whatever reason, they programmed the guardian with Nyarko's mind, causing the guardian to then obsess over Mahiro, giving the three a real excuse to destroy the machine and thus claim its not ready to protect Earth. Which would then allow them to continue guarding Earth a little longer and watch over Mahiro.
Mahiro spends a lot of time keeping Nyarko's advances at bay. In episode 5 of season 2, he quietly mentions that if she wasn't so aggressive in her pursuit of him, he'd probably like her, although Nyarko doesn't hear it. And in episode 6, he tells her to tone it down a little bit during her Anguished Declaration of Love, which she totally ignores the next morning.
Nyarko does the same towards Cuuko.
Nominal Hero: While technically a space cop doing her job, Nyarko is protecting Mahiro out of a crush, takes on the bad guys with too much enthusiasm and does a little personal smuggling of the kind she's supposed to stop.
Nyarko: "It's not a crime if no one finds out."
Not-So-Innocent Whistle: Gets used three times in the first season, each with the same subversion: the person in question can't whistle, resulting in Not-So-Innocent Blowing Noises.
When Yoriko arrives home at the beginning of Episode 4, the first thing she sees is her son pinning one girl to the ground (and positioned between her legs) while another clings to his back. Of course, he was really trying to kick Nyarko and Cuuko out before his mother came home.
Offscreen Moment of Awesome: In the opening for episode 3 of W (season 2), Nyarko charges a large group of aliens/monsters. Then the opening credits roll, and after its done, the scene cuts back to the characters standing around all of the defeated aliens/monsters Nyarko presumably beat up.
Otaku Surrogate: Nyarko shares the same obsession her race has with Earth (specifically, Japanese) entertainment.
Overt Operative: Despite taking human forms, Nyarko, Cuuko, and Hasta use their real names when introducing themselves to Mahiro's class. Nyarko even goes so far as announce that she travels the stars and fights villainous deities.
Parental Abandonment: Mahiro lives alone largely because his parents travel a lot. His mom does return home occasionally however, and is seen more in season 2.
His father's absence is explained in episode 4, where Yoriko says that he's going to be stuck at the office for a while making up the vacation days he took off for their latest honeymoon.
Phantom Zone: The "convenient barrier" Nyarko uses to fight in privacy.
Plot Tailored to the Party: Occurs unintentionally in episode 9 of Nyarko-San W, where the villain Agent Smith challenges Mahiro's group to a series of games in order to free the school from his hypnosis. Smith picks the games he thinks he can win easilynote including Daifugō, Mahjong, and Darts, but ends up losing because Nyarko and Mahiro are just plain better. Played the straightest with the game of Darts, which Mahiro handily owns thanks to his fork-throwing skills.
Power Levels: Jokingly referenced in the first novel, where Nyarko claims that she's one of the strongest fighters on Earth with a Fighting Power of 530,000note For DBZ fans, that's equal to Frieza's first form; she even mentions that an ordinary farmer with a hunting rifle has a Fighting Power of 5.
Season 2's first episode aired fairly soon after said series' anime had just ended, so when they returned to the shop, there are posters for it all over the place.
Taking this to Mind Screw levels, you can actually spot posters for Nyarko-san itself in that scene.
In season 2's second episode, Mahiro randomly finds a copy of the Heaven's Memo Pad light novel from a bookshelf at the Celaeno Library. It plays a key role in the next episode.
The miscellaneous "Nyarko Goods" Nyarko gives to Mahiro, including the Yes/No Cushion and body pillow, do exist in the real world; in fact, the body pillow scene happens in the light novel as well, but the illustration uses the more NSFW side.
Cuuko's "dun-wich". Lampshaded when Mahiro responds "You don't have to force yourself to make bad jokes, you know".
The title of Episode 7 is Blue Coral Reef, which in Japanese is "Aoi SANgoshō".
And a subtle one in the title alone: Haiyore! Nyarko-SAN.
Race Against the Clock: Used in Remember my Love(craft-sensei). After the initial short is over, it cuts to a scene of a massive Borg-ish ship heading towards Earth, with the days left "Until The End Of Mankind". Then again, the shorts have nothing to do with the ship, until the last episode or so.
Real Place Background: Nodens' auction house front just looks like the Sagrada Familia, a famous church and touristic spot of Barcelona, Spain.
Red Herring: Ghutatan is shown lounging around an observation deck even as Mahiro fruitlessly searches for Nyarko and company amidst the "Groundhog Day" Loop he has just woken up to. Turns out that scene is just part of an overall Shout-Out to Urusei Yatsura, and Ghutatan is just as much a victim of the time loop as Mahiro.
In episode 9 of season 2, the school is taken over and the main characters at first blame Cuune since they're attacked by fire guardians. They end up running into another Cthuguhan who challenges them to a contest in order to release the students, or force them to take part if they lose. It turns out Cuune had nothing to do with any of this, since she was off getting the newest Dagomon game.
That same episode ends with both Nyarko and Mahiro remarking that they thought the Cyclone Vacuum would end up being the Chekhov's Gun that saved the day, especially after all the build-up it was give.
Ret Gone: In one of the later novels, Nyarko and Cuuko get written out of existence by Nyogta, a grade-school classmate of theirs who they beat up for bullying Hasta. Mahiro and Yithka end up going back in time in order to Set Right What Once Went Wrong.
Rubber Face: Nyarko does this to Kuuko in episode 9 of season 2.
Rule 34: In the first episode of Nyarko-San W, Mahiro is horrified to discover that this rule applies to him, as an alien Doujin circle wrote a Boys Love manga with him as the "star". Nyarko, Cuuko, and Hasuta fight over it until Mahiro buys it and destroys it.
Saying Too Much: In the Nyaruani episode "Cooking", Nyarko's recipe for Cooked Whole *BLEEP* revolves around an ingredient that's really hard to get thanks to the Space Washington Treaty; immediately after saying this, she thinks to herself "Crap, I shouldn't have said that."
Schoolgirl Lesbians: Cuuko has a one-sided crush on Nyarko. More of a post-schoolgirl case since both have already graduated from space elementary school but attend Mahiro's alma mater, Boryo Municipal High School to keep an eye on him.
Serious Business: The entities of the Cthulhu mythos view Earth's entertainment as this to the point where there's laws regarding how much can be taken from Earth, smuggling involving it, and some psychotic Moral Guardians feeling it being a bad influence is such a big that they should destroy the entire Earth.
Sesquipedalian Loquaciousness: Playing with Lovecraft's taste for colorful, archaic adjectives and words, Nyarko sometimes gives ominous, long descriptions of mundane things. For example, after Mahiro alerts her to a Nighgaunt attack with a bump on the head...
Nyarko: "I'm suffering from abnormal and blasphemous amounts of ominously chaotic pain."
Sick Episode: Nyarko catches a fever in episode 10 of season 2.
Single-Target Sexuality: Nyarko and Hasuta towards Mahiro, and Kuuko towards Nyarko. Subverted with Kuuko who falls for Mahiro.
Slapstick Knows no Gender: The comical abuse actually comes from Mahiro using a fork to stop Nyarko's crazed binges and unsolicited advances.
Small Reference Pools: Those not familiar with the expanded Mythos won't know Cthugha or Atlach-Nacha. As a result, some have mistaken Cuuko as Cthulhu because of the similarities of their names. Also, Elder Gods, Great Old Ones and Outer Gods are not synonymous.
Space Police: The Planetary Defense Organization has sent Nyarko to stop a smuggling and human-trafficking ring.
SpaceX: Nyarko and Cuuko refer to the alien equivalents of CQC, Kindergarten, etc. by simply adding the word "Space" before them.
Spell My Name with an S: It's bad enough that the Great Old Ones have unpronounceable names. Now transliterate those names in katakana, and discover why Nyarko, Cuuko, and Hastua are spelled inconsistently.
For Nyarko, her name is supposed to be "Nyarlathotep" combined with the Japanese suffix "-ko", which makes a name feminine. That means Nyaruko, Nyarko, and Nyarlko are all perfectly valid English spellings (until Aisora-sensei steps in and clarifies which one is correct).
Squee: In the first episode of the 2012 series, all the girls in Mahiro's P.E. class do a simultaneous Squee when Tamao (falsely) says that Mahiro admitted to being attracted to Nyarko.
The Staff Thinks of Everything: Episode 11 of the second anime ends with Mahiro finds himself in a world where there are no other people; after this episode aired, the image on the Nyarko-san homepage (the one at the top of this page) was replaced with one that showed Mahiro in the same pose, but none of the other characters; it reverted to normal after episode 12.
During the run of Nyarko-San W, episode 7 was delayed a week due to the 2013 World Table Tennis Championship; the staff responded by editing the website's front page so that Nyarko and Cuuko were holding table tennis paddles.
Starfish Aliens: Nyarlathotepians, Chtughans, etc. are actually abominations the human mind cannot grasp without going insane. The human forms they take are quite pleasant, though.
In episode 12, after Mahiro gets his wish to get some peace and quiet, he begins to miss the other characters despite his complaints about them.
In episode 6 of season 2, Nyarko returns to her former Genki Girl mood after being reassured by Mahiro that he doesn't hate her. She also traps Kuuko's cousin Kuune in another dimension when she gets rid of the room changer device she bought so the alien characters could have their own rooms inside Mahiro's house while the latter was sleeping after having an overnight gaming session with Kuuko.
Near the end of episode 12, season 2, Mahiro sighs and says that Nyarko, Kuuko, and Hasuta would always figure some excuse to stay on Earth and in his house.
Stop, or I Shoot Myself!: Isurugi, while inside Yoichi's body, does this to stop the main characters from trying to interfere in his plans in episode 10.
Strip Poker: In episode 7, Nyarko suggests playing this after Mahiro (in a desperate attempt to ignore her) suggests that he and Yoichi go play cards. This is what leads to the infamous Brutal Honesty and Heroic BSOD moments.
Suspiciously Similar Substitute: Zig-zagged. In episode 12 of season 2, while touring a factory where the new Earth guardian is being built, Mahiro and the others run into the chief engineer, Nodens, who was the first villain they encountered in the first season. However, despite looking and sounding exactly like the first guy, this Nodens claims he's not the same guy. But then he goes up to Mahiro and claims the boy would be good in some alien pornos, which was also what the first Nodens wanted to do to him. Nyarko's bosses then threaten to report him, causing him to back off and continue with the guardian demonstration.
Take a Third Option: In the last episode of Nyarko-san W, Nyarko asks Mahiro for a kiss (or a baby) as reward for fighting off the out-of-control Banshin. Yoriko comes up with another idea, suggesting that Mahiro pat her (as well as Cuuko and Hasta) on the head if they succeed. The trio deems this acceptable and heads off to kick robot butt.
Take That: In the light novel, Nyarko explains that the Cthulhu Corporation always pressures the Space Government for copyright term extension, so they keep their mascot Mr. Innsmouth from entering the public domain. Eventually the space governors get tired of the nagging and simply pass the Innsmouth Protection Act.
The various jammers and other gizmos used in Episode 10 are a clear dig at Gundam SEED's Neutron Jammer, Neutron Jammer Canceller, etc.
The main villain of episode 10 is a clear shot at Shintaro Ishihara, the governor of Tokyo and the man behind numerous obscenity laws aimed at cleaning up anime and manga.
Taking the Bullet: Nyarko (in Mahiro's body) does it for Mahiro (in her own body). Luckily she survives.
That Liar Lies: In episde 7, Mahiro desperately tries to convince everyone that Nyarko is lying when she claims to already be pregnant with their child. He fails, and even his own mother falls for it (though in her case, it might have been I Want Grandkids). When Hasta runs out of the room sobbing, Mahiro quietly remarks "Well, I guess it's okay for him to think it's true..."
Theme Tune Cameo: The first episode of Nyarko-san W has Nyarko drag Mahiro to a Cosplay Cafe with a karaoke machine, where we get to see her, Cuuko, and Tamao sing "Taiyo Iwaku Moeyo Chaos", the theme song for the first season. Mahiro lampshades the fact that Tamao apparently showed up just to sing and then immediately vanished.
"The Reason You Suck" Speech: Mahiro gives a couple to Nyarko, largely because of her antics and tendency to go overboard in various situations. His Brutal Honesty in episode 7 of the 2012 series probably qualifies.
In episode 6 of the second anime, Yoriko gives a less-insulting version to Luhy when she explains why the Xoth-731 console is doomed to failure. It's even funnier once you notice she's making very cogent points about the real-world game industry.
The Theme Park Version: In the Trapped in TV Land episode, Mahiro finds himself experiencing only the events one would encounter in a Dating Sim (like Christmas and Valentine's), causing him to "leap" randomly. It's never addressed if this holds true for the other people trapped in the game, but the fact that Nyarko apparently had the time to knit Mahiro a scarf for Christmas implies they didn't.
A Twinkle in the Sky: As is proper for a bumbling ineffective villain, Nyarko's brother is thrown over the horizon screaming.
Undead Tax Exemption: While they don't explicitly state they are aliens, none of the students at school seem fazed that they just happen to have three transfer students all join their class in a very short period of time.
Useful Notes: Japanese Language: Most of the time, when Nyarko says "I love you" to Mahiro, she says "daisuki" (大好き), which literally means "like a lot" and is generally regarded as the acceptable way of saying you love someone or somethings; in some contexts it can even come off as joking, since it's just "big" plus "like". During her emotional breakdown in Nyarko-San W episode 6, however, she uses "aishiteru" (愛してる), which has much stronger connotations, and tends to only be used in romantic fiction; it's about as serious a declaration of love as a person can make, and shows that she's taking all her silly behavior off the table and trying to show Mahiro that she really means what she's saying.
Wake Up, Go to School, Save the World: Nyarko, Cuuko, and Hasta don't have to do the "go to school" part, since they're adults and have already graduated from space college; they just like being around Mahiro. He, on the other hand, plays the school part straight but tends to get dragged into the "save the world" part by the trio.
Nyarko (while in Mahiro's body) delivers one to Mahiro (who is in Nyarko's body) in episode 9.
Mahiro: Nyarko, I love you!
Kuuko asks Mahiro one in episode 5 of season 2. It causes him to cut his finger as he was preparing some dinner.
Kuuko: Boy, do you like Nyarko after all?
In episode 12 of season 2, the first thing Nyarko says after entering her Heroic BSOD, and the point where the gravity of the situation finally hits Mahiro.
Nyarko: So does this really mean I have to leave Mahiro-san forever?
Weaksauce Weakness: The aliens in episode 10 of season 2 are defeated by the music coming from Nyarko's ringtone.
We Want Our Jerk Back: "How to Defeat a Kind Enemy" (a short story adapted into an OVA episode) has Mahiro try to get Nyarko to act like a Magical Girl instead of a Henshin Hero in the hopes that it'll make her act less crazy and violent. Unfortunately, she gets even worse, spouting cliché Magical Girl talk about "purifying souls" while lighting Nightgaunts on fire and making them vomit blood, so Cuuko and Mahiro neuralize her back to normal.
What the Hell, Hero?: After Mahiro's Wham Line in episode 7, Nyarko suffers from a long lasting Color Failure. Which prompts his mom to ask him if she really is that awful, since she has been saving his life and saved hers as well. She essentially forces him to take her on a date to make up for hurting her feelings.
When Mahiro's mother is being kidnapped in episode 5, Cuuko forms a fire barrier around the house so Nyarko can't get in. Nyarko says that everything can be solved with a karate kick, and proceeds to kick it, only to hilariously burn her foot in the process.
Mahiro and his forks. Nyarko, Kuuko, and Hasuta seem deathly afraid of it, and he even buys some for his mom who uses them during her adventuring.
You Have Outlived Your Usefulness: The Yith creature in episode 10 tells this to Isurugi (who is inside Yoichi's body) in episode 10 after the latter creates a device which he thought was going to transplant Yith beings into humans so they could experience human and Earth culture first-hand. Instead it turns out to be a portal where the Moral Guardian can destroy Earth because its corrupting space morals.