[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/jinrui_461.jpg]]
[[caption-width-right:350:[-[[NoNameGiven The U.N. Mediator and Her Assistant.]]-] ]]

''Jinrui wa Suitai Shimashita'', translated as "Humanity has Declined", is a light novel written by Romeo Tanaka and an Anime animated by studio {{AIC}} A.S.T.A.

For years, declining birth rates have forced what’s left of the human race to cede more and more territory to other beings who have appeared to take advantage of the emptying ecological niche. Now, only a handful of humans remain among the remnants of civilization and Earth is dominated by fairies – tiny, four-inch tall creatures of surprising intelligence. But humanity’s importance isn’t over quite yet, as the young [[NoNameGiven heroine]] learns as she makes the decision to return to her hometown and assume her grandfather’s position as an arbitrator between the races. Unfortunately, the job isn’t going to be anywhere near as simple as she expected, and it’s going to take a wisdom far beyond her years to achieve her most important mission.

Originally a light novel, an anime adaptation premiered as a part of the Summer2012Anime lineup and is currently being simulcast on [[http://www.crunchyroll.com/humanity-has-declined Crunchyroll]]. It has been licensed by SentaiFilmworks with a home video release planned for 2013.
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!!This series contains examples of:

* AcmeProducts: Fairy Co.
* AdultsAreUseless: They are when investigating Fairy Co. anyhow.
* AfterTheEnd: Humanity seems to be living in the aftermath of some previous catastrophe, with the technological level being reverted, knowledge having been lost, ruined and abandoned structures scattered all over the countryside, and a very small human population that is on the brink of extinction. While the catastrophe that caused this has been mentioned several times, it's never explicitly stated what it was.
** The Heroine once alludes to the fairy about how the Old Humanity (homo sapiens) were destroying themselves through war and overexploitation of resources.
* AloofDarkHairedGirl: {{Deconstructed}}. The reason the protagonist was this in school is because it's a psychological defense against a toxic environment. She's deliberately being nasty as a social firewall, which others somehow interpret as charming.
** Y was also like this for somewhat different reasons. She genuinely did want friends [[spoiler:who weren't as messed up as the Wild Rose Society]] and didn't want to reveal [[YaoiFangirl her hobby]] to others.
* AnachronicOrder: The arc order is Secret Tea Party (flashback) => Earth => Time Management => Homecoming => Secret Factory => Survival Skills => Secret Tea Party (frame) => Subculture.
* AnthropomorphicFood: Disturbingly used first with headless, plucked chickens, then with...[[FutureFoodIsArtificial carrot "bread"]].
* AsideGlance: Appears less often than one would expect from someone with the heroine's snark level, but it does appear.
* AwesomeMcCoolname: One fairy decides to name himself Sir Christopher [=McFarlane=] in episode 10.
* BananaPeel: Used to create a [[{{Pun}} time slip]].
* BeYourself: [[InvertedTrope Inverted]]! [[spoiler:Due to Assistant-kun's upbringing, he's a total BlankSlate, and thus seeks others to define him. With some help from the fairies, he manage to come up with a functional enough identity.]]
* BeneathTheMask: [[spoiler: The Wild Rose Society serves as the mask for its members, each of whom, barring Y and the heroine, are varying degrees of bat-shit crazy.]]
* {{Bizarrchitecture}}: Fairy-built structures tend to be odd.
* BizarreAlienBiology: Fairy urine is essentially pure-water. Yep.
* BizarreAlienReproduction: Fairies reproduce by getting happy. It's not clear how this works. No, this is not an euphemism.
* BlackComedy: At times. Most obvious with poor, poor Loaf-kun.
** [[spoiler:It doesn't stop there. The majority of the headless and skinned chickens, true masters of the Fairy Co, are finished by being made into products. It's horrifying as it is hilarious.]]
** Assistant's picture book in episode two of the anime.
* BlankSlate: [[spoiler:Assistant started as this. The effects are weirder than usual.]]
* BlatantLies: Pion and Oyage insist that they're human (until they get their memories back anyway).
* BleachedUnderpants: Prior to writing the light novels, Tanaka Romeo was well known for writing the scenarios for {{H-Game}}s of the [[{{Utsuge}} depressing]] PornWithPlot variety. Much of the CringeComedy remains, however.
* BlobMonster: Appears in the Homecoming arc. When not feral and aggressive, they appear to be some form of advanced, shapeshifting technology.
* BloodyHilarious: Technically carrot juice, but the effect is the same.
* BoardingSchool: The setting of the Secret Tea Party arc.
* BrickJoke: [[spoiler:The green-clad fairy from the Secret Tea Party arc]]. It's great that they essentially have infinite lifespan to pull this kind of joke.
* TheChrisCarterEffect: [[invoked]] Parodied heavily in Episode 4, where Y explains that the way to make a bestselling manga is not to craft a consistent plot, but to keep stringing viewers along with constant cliffhangers, since they won't realize the plot holes until the end. However, once the audience catches on, the popularity of their manga drops like a stone.
-->''The greatest entertainer is the greatest swindler!''
* ClockRoaches: The Time Paradogs, kind of. No, they are not like [[CthulhuMythos Hounds of Tindalos]]-- they are nice doggies.
* {{Cloudcuckoolander}}: An entire Cloudcuckoolander subspecies of humanity exists, with their thoughts making little sense to the audience. [[BaitAndSwitch Then there are the fairies]], who take things {{up to eleven}}.
* CombatTentacles: Used by the [[MakesJustAsMuchSenseInContext giant fairy nautilus]] in episode six.
* ConspicuousCG: The secret hall in the Tea Party arc.
* CosyCatastrophe: No one seems to mind the fact that the manufacturing technology is lost to the mist of time.
* CovertPervert: [[spoiler:The Witch from Wild Rose Society. She collects hair strands of fellow students, and has a special fondness of the Heroine's.]] She naturally freaks out when it's revealed.
* CuteMute: Assistant. [[spoiler:He speaks at the end of episode eight. Given his nature, he's probably just very quiet.]]
* CrapsaccharineWorld: The pastel-colored world clashes with the atmosphere of mankind's twilight.
** WorldHalfFull: Really, they're taking the whole "being driven to extinction" thing pretty well.
* DetachedSleeves: Pion has them.
* [[DisturbedDoves Disturbed Seagulls]]: Done in the climatic scene of the second episode, where Assistant finishes off the [[spoiler:skinless chickens]].
* TheDogWasTheMastermind: The mysterious higher-ups of Fairy Co. are... [[spoiler:skinless chickens]].
* {{Doujinshi}}: The premise of episode three.
** DuelingProducts: In-Universe example: Y's revival of the Doujin Manga creates unwanted competition for her own publication.
* DrivesLikeCrazy: Y.
* DyingRace: As indicated by the title, humankind itself, though it does still have a few good years ahead of it.
* DysfunctionJunction: [[spoiler:Wild Rose Society.]] When it's revealed, one can't help but think that the author has [[TakeThat a bone to pick]] with [[spoiler:''LightNovel/MariaSamaGaMiteru'']].
* EternalEngine: The factory that churns out Fairy Co products. The design is hipster-sleek, but one can't help but feel that it's inhumanly sterile.
* EvilGloating: The [[spoiler:chickens]] are good at it. Unfortunately, the heroine was too busy adjusting the subtitles.
** EvilIsHammy
* TheFairFolk: The fairies are a less malicious and more childlike version of this. They don't exactly play by human rules, so they're not above [[spoiler:causing {{Stable Time Loop}}s for sweets]].
* FirstPersonSmartass: The heroine.
** DeadpanSnarker
* FrozenFace: Fairies only ever show a giant, empty grin [[spoiler:except for the transformed Heroine]].
* GangOfBullies: Frequently seen in the boarding school.
* GenreRoulette
* AGodAmI: Inverted! After being declared a god by the fairy, the protagonist starts to feel uneasy, and quickly passes the baton to someone else.
* GratuitousEnglish: Scattered about. Mostly from the heroine and the fairies. May be something she picked up from them.
* GreenAesop
** The Secret Factory arc seems to have one.
** In Survival Skill episode the Queendom antics proceed as long as there are trees left to fuel it. With last tree on the island chopped, things go downhill.
* GroundhogDayLoop: The Time Management arc is set in one.
* HiddenPurposeTest: Orchestrated by Y early on in Secret Tea Party arc. Having solved one riddle, the heroine sees the second. The only incentive being a key to an extra lock on her dorm room door, the heroine opts to break inside. Years later, it is discussed between the two: Y decided that the heroine didn't have the smarts to pass the test, the heroine claims she knew the answer, but wouldn't bother acting on it, seeing the risk of there being even more of these boring riddles.
* {{Hikikomori}}: The city that's the main setting of the Homecoming arc [[AfterTheEnd was]] apparently a cultural version of this. They locked themselves in out of fear of EM waves.
* HopelessBossFight: Set-up when [[MakesJustAsMuchSenseInContext Oyage uses the Slime to turn into a giant cat monster]]. In response the heroine bows down and surrenders, to Oyage's surprise.
* HumongousMecha: The fairies build one in episode 10. Being fairy-scaled, it's about the size of a human.
* IdiosyncraticEpisodeNaming: Every episode (or set thereof) starts with 「妖精さんたちの、」/"Yousei-san-tachi no,"/"The fairies'".
* ImportantHaircut: {{Inverted}}. It's after experiencing firsthand the potency of Fairy Co. hair growth tonic that the heroine begin to be interested in Fairy Co., thus starting the adventure.
** The reason for the short hair appears [[AnachronicOrder in episode 6]]. It's a punishment for [[spoiler:sabotaging the generator so that Pion and Oyage don't have to leave.]]
* IncrediblyLamePun: See ShaggyDogStory and StealthPun below.
* JustBeforeTheEnd: Not really clear why, but humanity is expected to go extinct reasonably soon.
* {{Kemonomimi}}: Pion has ''some'' kind of animal ears.
* KidsAreCruel: Basically the point of episode 11
* LargeHam: The Director, [[spoiler:the chickens]], Y, Oyage... Most side characters in general, really.
** [[TheTropeKid The Ringo Kid]] deserves a special mention for being [[spoiler:the past self of a not nearly as hammy Grandfather.]]
* LetsMeetTheMeat: The bread-robot guide in the fully-automated factory. He even rips himself apart in his belief that he's not delicious, resulting in red (carrot juice) mess everywhere.
** [[spoiler:The real masters of the factory are the sentient, mobile skinless chickens with a plan to take over the world.]]
* LevelAte: The island nation in episode 9 briefly becomes this after the fairies discover how to breed plants that make sweets.
* LinkedListClueMethodology: Happens to the heroine in episode 11 with the key to a lock on her dormitory room door. [[spoiler: Two steps in, she sees it forming, decides it's not worth the effort and [[TakeAThirdOption finds another solution]].]]
* LittlePeople: The fairies. "Little" here meaning maybe 10 centimeters tall.
* LostTechnology: In the abandoned city in the Homecoming arc.
* LovableSexManiac: The Ringo Kid certainly qualifies [[spoiler: though he seems to have calmed as Grandfather.]]
* MagicFromTechnology: Or possibly {{Magitek}}. The fairies use sciencey terms to talk about things that'd normally be supernatural.
* MegaNeko: Oyage uses the slimes to turn into one. This makes ''slightly'' more sense in context.
* MesACrowd: The Time Management arc ultimately has several dozen instances of the heroine in the same place.
* MindScrew: A lot of the plot, especially episode seven.
* MoeAnthropomorphism: Pion and Oyage are [[spoiler:deep space probes]] that look like attractive humans. How this happened isn't clear.
* MoonLogicPuzzle: How Y expected ''anyone'' to solve her puzzles isn't clear.
* MotorMouth: Oyage describing his bulldozer.
* NoNameGiven: All of the major characters, and a number of minor characters, almost to the point of being a NamelessNarrative. "[[UsefulNotes/JapanesePronouns Watashi]]" and "Assistant" aren't their actual names, obviously. The English-speaking fandom hasn't really settled on a nickname for the main character, using "Watashi" (which she's credited as), "Mediator", "the protagonist", "the heroine", and similar variably.
** EveryoneCallsHimBarkeep: The general result of the above.
* OjouRinglets: "Curly" has them.
* OnceMoreWithClarity[=/=]MindScrewdriver: Basically, the entire eighth episode to the seventh.
* OneeSama: How Curly refers the heroine. She doesn't exactly like it.
* OneLetterName: Y.
* OurFairiesAreDifferent: Tiny, addicted to sweets, evolved from humans, don't act at all bright despite apparently having super-advanced technology, and have permanent vacant grins. No wings, either.
* PersonalRaincloud: The fairies get these. They really exist [[spoiler:and can actually become the weather if you get enough of them in one place]].
* {{Pixellation}}: The diary of Witch of the Wild Rose Society has [[NoNameGiven "names"]] mentions courteously blurred out. [[PlayedForLaughs By pixellation so weak, you can still read it]].
* PlaceBeyondTime: The hearth in the forest. Which the fairies created as part of a scheme to get more sweets.
* PowerSource: Oyage and Pion require a certain amount of energy in order to function. Once they run out they turn into small black slabs.
* PrehensileHair: [[spoiler: A side-effect of the hair-growth tonic]]. Also has SuperStrength and a mind of its own, but is thankfully loyal to its master.
* RapunzelHair: The heroine.
* RagnarokProofing: A remarkable amount of pre-decline technology still works.
** This is briefly discussed regarding the Human Monument Project, as they say that digital media tends not to last as long.
* RedOniBlueOni: The heroine, as the latter, and Y, as the former.
** Also, Pion and Oyage. Pion as the stricter, more by-the-book Blue Oni, an Oyage as the renegade Red Oni.
* RidiculouslyHumanRobots: Pion and Oyage. Either makes more or less sense than usual as [[spoiler:they were (presumably) designed by themselves]].
* RobotDog: Appears in episode 5. Quite vicious.
* RobotGirl: Pion
* RoomFullOfCrazy: The manga panels in episode four could be considered these.
* RuinsOfTheModernAge
* {{Satire}}: Episodes 3 and 4 are both a parody and critique of modern doujinshi and manga business practices, respectively.
* SceneryGorn: The dump in episode 10 is some well-drawn waste.
* SecretPassage: The school dorms has one that leads into most of the rooms.
* ShoutOut : A in episode 4 there is a fight in the [[SaintSeiya Sanctuary]], when using armors.
** In Ep. 6, Oyage is briefly dressed as a [[Franchise/BioShock Big Daddy]].
** Another pone at Ep. 10, when Watashi goes through the notes of her Grandfather's predecessor, they show in a display similar to the Franchise/ResidentEvil Files
* ShownTheirWork: Episode 6 references the [[http://en.wikipedia.org/wiki/Pioneer_anomaly Pioneer Anomaly]], though the show explains that the effect was caused by [[spoiler:the fact that Pioneer was self-aware, and hesitated because it didn't want to go out in the cold, empty void of space and leave Earth behind forever.]]
* TheSilentBob: The heroine seems to be able to understand Assistant even when he isn't using signs.
* SlowMotionFall: [[spoiler:The chickens after their EvilGloating to the heroine, when Assistant starts taking pictures of them causing them to panic.]]
* SoundtrackDissonance: ''Ave Maria'' plays as Assistant finishes off the [[spoiler:skinless chickens]] by shooting them [[spoiler:with his camera]]. ShoutOut to ''VideoGame/{{Hitman}}'', maybe.
* SplashPanel: Comes up during Episode 4 and its parody of manga. Fancy art only goes so far...
* StealthPun: The fairies created special bananas to induce time slip, which is possible due to the existence of time paradogs...
* SteamPunk: Well, there's a steam car, at least.
* SupremeChef: The heroine, at least when it comes to sweets.
* SurrealHumor: And sometimes the humor is CringeComedy.
* [[SuspiciouslySpecificDenial Suspiciously Specific Prescription]]: “Fairy Co. Hair Growth Medication. Perfect for someone who had to cut their hair after losing a bet!”
* StableTimeLoop: Implied in episode eight: [[spoiler:Grandpa stole the sundial watch from the heroine when she got sent back way too far in the past.]]
* SuicideAsComedy: [[spoiler:Loaf-kun...]]
* SweetTooth: ''The fairies.''
* TalkingWithSigns: Assistant does this occasionally.
* TheoryOfNarrativeCausality: Having fairies around causes this, apparently.
* TimeParadox: There can't be an original wrist-sundial...
* TheTropeKid: The Ringo Kid.
* TsurimeEyes: Y.
* UsefulNotes/UnitedNations: The heroine is a U.N. Mediator, whatever that might mean in this story.
* UnwantedFalseFaith: The fairies in episode 10 end up deciding to deify the heroine. She doesn't like the idea.
* UnspecifiedApocalypse: The human race is slowly dying out; exactly why is never spelled out, and the humans seem no worse than melancholy about the notion.
* VagueAge: The protagonist started secondary school late but skipped grades, getting to [[https://en.wikipedia.org/wiki/Sixth_form sixth form]] quickly.
* VocalDissonance: The wanderer fairy. Cute little body, raspy voice.
* VoluntaryShapeshifting: The fairies in general have demonstrated the ability to turn into balls, and at least one can turn into a ring.
* WallOfWeapons: The Camphorwood UN building has a wall of guns for some reason. It may be a remnant of when humanity was still waging wars.
* WeaksauceWeakness: Microwaves kill fairies. They're lucky it's AfterTheEnd...
* WhenItAllBegan: Episode 10 shows the heroine's first job as a Mediator. Episode 11 goes back further, showing her school days and [[spoiler:the first fairy she met]].
* WhiteVoidRoom: The result of getting sucked into an unfinished manga.
* WholeEpisodeFlashback: The Secret Tea Party.
* WidgetSeries: A defining example.
** ''Especially'' the Homecoming arc. The strangeness wasn't even made by [[AWizardDidIt the fairies]]!
* WildChild: Assistant, apparently. It doesn't really show aside from being mute.
* XMeetsY: ''Manga/YokohamaKaidashiKikou'' meets ''Anime/ALittleSnowFairySugar''.
* {{Yandere}}: [[spoiler:'''CURLY'''.]] for the protagonist.
* YouGottaHaveBlueHair: Characters are not limited to natural hair colours. Justified for the fairies, not justified for Old Humanity.
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