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Light Novel / Humanity Has Declined

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Humanity Has Declined, known in Japanese as Jinrui wa Suitai Shimashita, is an eleven-volume light novel series written by Romeo Tanaka which ran from May 24, 2007 to September 16, 2016.

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 child-like creatures of surprising intelligence. But humanity’s importance isn't over quite yet, as the young 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.


An anime adaptation by studio AIC A.S.T.A. premiered as a part of the Summer 2012 Anime lineup and was simulcast on Crunchyroll. It was licensed by Sentai Filmworks with a home video release in 2013. There are also three separate manga adaptations written by Romeo Tanaka himself.


  • Acme Products: Fairy Co.
  • Adults Are Useless: They are when investigating Fairy Co., anyhow.
  • After the End: 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 very small, scattered human populations that are 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.
    • That said, the catastrophe could be the population collapse itself. Any given technological level has a minimum population in order to be sustainable—the declining birth rates alone would, over time, do the job all on its own.
  • Aloof Dark-Haired Girl: 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 who weren't as messed up as the Wild Rose Society and didn't want to reveal her hobby to others.
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  • Anachronic Order: The arc order is Secret Tea Party (flashback) => Earth => Time Management => Homecoming => Secret Factory => Survival Skills => Secret Tea Party (frame) => Subculture.
  • Anthropomorphic Food: Disturbingly used first with headless, plucked chickens, then with... carrot "bread".
  • Aside Glance: Appears less often than one would expect from someone with the heroine's snark level, but it does appear.
  • Awesome Mc Coolname: One fairy decides to name himself Sir Christopher McFarlane in episode 10.
  • Banana Peel: Used to create a time slip.
  • Be Yourself: Inverted! Due to Assistant-kun's upbringing, he's a total Blank Slate, and thus seeks others to define him. With some help from the fairies, he manages to come up with a functional enough identity.
  • Beneath the Mask: 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.
  • Bizarre Alien Biology: Fairy urine is essentially pure-water. Yep.
  • Bizarre Alien Reproduction: Fairies reproduce by getting happy. It's not clear how this works. No, this is not an euphemism.
  • Black Comedy: At times. Most obvious with poor, poor Loaf-kun.
    • 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.
  • Blank Slate: Assistant started as this. The effects are weirder than usual.
  • Blatant Lies: Pion and Oyage insist that they're human (until they get their memories back anyway).
  • Bleached Underpants: Prior to writing the light novels, Tanaka Romeo was well known for writing the scenarios for H-Games of the depressing Porn with Plot variety. Much of the Cringe Comedy remains, however.
  • Blob Monster: Appears in the Homecoming arc. When not feral and aggressive, they appear to be some form of advanced, shapeshifting technology.
  • Bloody Hilarious: Technically carrot juice, but the effect is the same.
  • Boarding School: The setting of the Secret Tea Party arc.
  • Brick Joke: 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.
  • The Chris Carter Effect: 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!
  • Clock Roaches: The Time Paradogs, kind of. No, they are not like Hounds of Tindalos— they are nice doggies.
  • Cloudcuckoolander: An entire Cloudcuckoolander subspecies of humanity exists, with their thoughts making little sense to the audience. Then there are the fairies, who take things Up to Eleven.
  • Combat Tentacles: Used by the giant fairy nautilus in episode six.
  • Cosy Catastrophe: No one seems to mind the fact that manufacturing technology is lost to the mists of time.
  • Covert Pervert: 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.
  • Cute Mute: Assistant. He speaks at the end of episode eight. Given his nature, he's probably just very quiet.
  • Crapsaccharine World: The pastel-colored world clashes with the atmosphere of mankind's twilight.
  • Disturbed Seagulls: Done in the climatic scene of the second episode, where Assistant finishes off the skinless chickens.
  • The Dog Was the Mastermind: The mysterious higher-ups of Fairy Co. are... skinless chickens.
  • Doujinshi: The premise of episode three.
    • Dueling Products: In-Universe example: Y's revival of the Doujin Manga creates unwanted competition for her own publication.
  • Drives Like Crazy: Y.
  • Dying Race: As indicated by the title, humankind itself, though it does still have a few good years ahead of it.
  • Dysfunction Junction: Wild Rose Society. When it's revealed, one can't help but think that the author has a bone to pick with Maria Watches Over Us.
  • Eternal Engine: 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.
  • Everyone Calls Him "Barkeep": The general result of No Name Given.
  • Evil Gloating: The chickens are good at it. Unfortunately, the heroine was too busy adjusting the subtitles.
  • Evil Is Hammy
  • The Fair Folk: 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 causing Stable Time Loops for sweets.
  • First-Person Smartass: The heroine.
  • Frozen Face: Fairies only ever show a giant, empty grin except for the transformed Heroine.
  • Gang of Bullies: Frequently seen in the boarding school.
  • Genre Roulette
  • A God I Am Not: After being declared a god by the fairy, the protagonist starts to feel uneasy, and quickly passes the baton to someone else.
  • Gratuitous English: Scattered about. Mostly from the heroine and the fairies. May be something she picked up from them.
  • Green Aesop:
    • The Secret Factory arc seems to have one.
    • In the Survival Skill episode the Queendom antics proceed as long as there are trees left to fuel it. With ever last tree on the island chopped down, things quickly go downhill.
  • "Groundhog Day" Loop: The Time Management arc is set in one.
  • Hidden Purpose Test: 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 was apparently a cultural version of this. They locked themselves in out of fear of EM waves.
  • Hopeless Boss Fight: Set-up when Oyage uses the Slime to turn into a giant cat monster. In response the heroine bows down and surrenders, to Oyage's surprise.
  • Humongous Mecha: The fairies build one in episode 10. Being fairy-scaled, it's about the size of a human.
  • Idiosyncratic Episode Naming: Every episode (or set thereof) starts with 「妖精さんたちの、」/"Yousei-san-tachi no,"/"The fairies'".
  • Important Haircut: 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 in episode 6. It's a punishment for sabotaging the generator so that Pion and Oyage don't have to leave.
  • Incredibly Lame Pun: See "Shaggy Dog" Story and Stealth Pun below.
  • Just Before the End: Not really clear why, but humanity is expected to go extinct reasonably soon.
  • Kids Are Cruel: Basically the point of episode 11
  • Kudzu Plot: An in-universe one occurs during episode 4, with Y deliberately introducing more and more twists and cliffhangers to keep the manga's popularity afloat. Once the strategy stops working and the manga's popularity starts plummeting, the cast resorts to hasty explanations to try and tie up the numerous plot points of their genre-spanning story.
  • Large Ham: The Director, the chickens, Y, Oyage... Most side characters in general, really.
    • The Ringo Kid deserves a special mention for being the past self of a not nearly as hammy Grandfather.
  • Let's Meet the Meat: 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.
    • The real masters of the factory are the sentient, mobile skinless chickens with a plan to take over the world.
  • Level Ate: The island nation in episode 9 briefly becomes this after the fairies discover how to breed plants that make sweets.
  • Linked List Clue Methodology: Happens to the heroine in episode 11 with the key to a lock on her dormitory room door. Two steps in, she sees it forming, decides it's not worth the effort and finds another solution.
  • Little Bit Beastly: Pion has some kind of animal ears.
  • Little People: The fairies. "Little" here meaning maybe 10 centimeters tall.
  • Lost Technology: In the abandoned city in the Homecoming arc.
  • Lovable Sex Maniac: The Ringo Kid certainly qualifies though he seems to have calmed as Grandfather.
  • Magic from Technology: Or possibly Magitek. The fairies use sciencey terms to talk about things that'd normally be supernatural.
  • Mega Neko: Oyage uses the slimes to turn into one. This makes slightly more sense in context.
  • Me's a Crowd: The Time Management arc ultimately has several dozen instances of the heroine in the same place.
  • Mind Screw: A lot of the plot, especially episode seven.
  • Moe Anthropomorphism: Pion and Oyage are deep space probes that look like attractive humans. How this happened isn't clear.
  • Moon Logic Puzzle: How Y expected anyone to solve her puzzles isn't clear.
  • Motor Mouth: Oyage describing his bulldozer.
  • No Name Given: All of the major characters, and a number of minor characters, almost to the point of being a Nameless Narrative. "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.
  • Ojou Ringlets: "Curly" has them.
  • Once More, with Clarity!/Mind Screwdriver: Basically, the entire eighth episode to the seventh.
  • Onee-sama: How Curly refers the heroine. She doesn't exactly like it.
  • One-Letter Name: Y.
  • Our Fairies Are Different: 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.
  • Personal Raincloud: The fairies get these. They really exist 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 "names" mentions courteously blurred out. By pixellation so weak, you can still read it.
  • Place Beyond Time: The hearth in the forest. Which the fairies created as part of a scheme to get more sweets.
  • Power Source: Oyage and Pion require a certain amount of energy in order to function. Once they run out they turn into small black slabs.
  • Prehensile Hair: A side-effect of the hair-growth tonic. Also has Super Strength and a mind of its own, but is thankfully loyal to its master.
  • Rapunzel Hair: The heroine.
  • Ragnarök Proofing: 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.
  • Red Oni, Blue Oni: 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.
  • Ridiculously Human Robots: Pion and Oyage. Either makes more or less sense than usual as they were (presumably) designed by themselves.
  • Robot Dog: Appears in episode 5. Quite vicious.
  • Robot Girl: Pion
  • Room Full of Crazy: The manga panels in episode four could be considered these.
  • Ruins of the Modern Age
  • Satire:
    • Episodes 3 and 4 are both a parody and critique of modern doujinshi and manga business practices, respectively.
  • Scenery Gorn: The dump in episode 10 is some well-drawn waste.
  • Secret Passage: The school dorms has one that leads into most of the rooms.
  • Shout-Out : In episode 4, there is a fight in the Sanctuary, when using armors. There's also a scene where Y reenacts TK's temporary sacrifice with the falling ceiling.
  • Shown Their Work: Episode 6 references the Pioneer Anomaly, though the show explains that the effect was caused by 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.
  • The Silent Bob: The heroine seems to be able to understand Assistant even when he isn't using signs.
  • Slow-Motion Fall: The chickens after their Evil Gloating to the heroine, when Assistant starts taking pictures of them causing them to panic.
  • Soundtrack Dissonance: Ave Maria plays as Assistant finishes off the skinless chickens by shooting them with his camera. Shout-Out to Hitman, maybe.
  • Splash Panel: Comes up during Episode 4 and its parody of manga. Fancy art only goes so far...
  • Stable Time Loop: Implied in episode eight: Grandpa stole the sundial watch from the heroine when she got sent back way too far in the past.
  • Stealth Pun: 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.
  • Sudden Soundtrack Stop: During the bread scene, when it suddenly cuts back from Loaf-kun to the receptionist.
  • Suicide as Comedy: Loaf-kun...
  • Supreme Chef: The heroine, at least when it comes to sweets.
  • Surreal Humor: And sometimes the humor is Cringe Comedy.
  • Suspiciously Specific Prescription: “Fairy Co. Hair Growth Medication. Perfect for someone who had to cut their hair after losing a bet!”
  • Sweet Tooth: The fairies.
  • Talking with Signs: Assistant does this occasionally.
  • Theory of Narrative Causality: Having fairies around causes this, apparently.
  • Time Paradox: There can't be an original wrist-sundial...
  • The Trope Kid: The Ringo Kid.
  • Tsurime Eyes: Y.
  • United Nations: The heroine is a U.N. Mediator, whatever that might mean in this story.
  • Unwanted False Faith: The fairies in episode 10 end up deciding to deify the heroine. She doesn't like the idea.
  • Unspecified Apocalypse: The human race is slowly dying out; exactly why is never spelled out, and the humans seem no worse than melancholy about the notion.
  • Vague Age: The protagonist started secondary school late but skipped grades, getting to sixth form quickly.
  • Vocal Dissonance: The wanderer fairy. Cute little body, raspy voice.
  • Voluntary Shapeshifting: The fairies in general have demonstrated the ability to turn into balls, and at least one can turn into a ring.
  • Wall of Weapons: The Camphorwood UN building has a wall of guns for some reason. It may be a remnant of when humanity was still waging wars, or may reflect on Grandfather's own interest in firearms. Whatever the exact reason, there are several bullet holes in the wall opposite his desk, though we never see him fire a single shot.
  • Weaksauce Weakness: Microwaves kill fairies. They're lucky it's After the End...
  • When It All Began: Episode 10 shows the heroine's first job as a Mediator. Episode 11 goes back further, showing her school days and the first fairy she met.
  • White Void Room: The result of getting sucked into an unfinished manga.
  • Whole Episode Flashback: The Secret Tea Party.
  • Wild Child: Assistant, apparently. It doesn't really show aside from being mute.
  • A World Half Full: Really, they're taking the whole "being driven to extinction" thing pretty well.
  • Yandere: CURLY. for the protagonist.
  • You Gotta Have Blue Hair: Characters are not limited to natural hair colours. Justified for the fairies, not justified for Old Humanity.

Alternative Title(s): Jinrui Wa Suitai Shimashita


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