23rd Oct: It's time for the Second TV Tropes Halloween Avatar Contest! Details here.
Humanity itself is either downloaded into a computer brain simulation or off living elsewhere in the galaxy.Because it may feel slightly petty of me, but I don't want humanity to be going downhill. Most people on earth downloaded themselves/left for the stars, and the remaining folks decided that war, government, and all that bad stuff wasn't worth their time, so they just chill and let most of the world return to nature. Allows me to chill reading this without feeling a bit down.
Alpha was here long before the great flood, and Mr. Hatsuneno left before the flood as well.Alpha wouldn't consider this to be the twilight of mankind if not for prior knowledge of what kind of life mankind has lead before this.
The human race knows that it is doomed, and the Alpha series is designed to be their final legacy.You see fewer and fewer humans the further the series goes. Alpha is a living museum as to what humanity was, and so the next civilization, sentient race, or whatever aliens show up in the far future can have someone to learn about us from. This may be kinda obvious from the setting, but the reasoning behind the creation of the androids is never outright explained...
The human race built the Alphas, and then when the need arose, they set them to keeping the lights on while they went away and waited for the planet to sort itself out again. Some humans opt to stay behind to help maintain the infrastructure.
Yokohama Kaidashi Kikou ties into the Mega Man franchiseThis requires that either there are some humans left in the world (Dr. Light and Dr. Wily), or Dr. Light and Dr. Wily themselves are robots. Either way, most of the planet is populated by normal robots, and what we see in the Mega Man series are extraordinary robots granted special powers. Thus, Yokohama Kaidashi Kikou is a Slice of Life version of Mega Man following the lives of the more normal robots.
The world of Yokohama Kaidashi Kikou is a by-product of Instrumentality
The "ghost" that Ayase tells Alpha about (in Chapter 99: Surface of the Earth) is Alpha herselfAyase mentions that there are rumors of the area (where the cafe would later reside in) being haunted. He mentions that this was during his childhood, before the cafe was opened. It's likely these rumors started after passers-by noticed how unusually tidy such an otherwise derelict little town was and surmised that a spirit must be watching the area, unaware that the area's upkeep was Alpha's handiwork.
The global disaster that forms the setting of YKK was genetics run amokLong before the manga's setting, some scientists (or a group of scientists) set about on some breakthroughs in genetics research, principally genetic manipulation. Their motivations may have been varied: research for the sake of research, the solution to global agricultural depletion, the development of crops better suited for an environment afflicted with global warming.... Anyway, they created a plant or crop with adverse side effects. It quickly "broke out" and proliferated, disrupting the balance of the atmosphere's composition and aggravating the already serious global warming problem. It was able to cross-pollinate and hybridize with a wide variety of plant species; hence, the mushroom-like "shrines" and other people-like figures, plants imitating street lamps, and sunflowers three stories tall. Fauna became affected as well, as evidenced by the "kamas."
Misago is a genetically mutated human resulting from the described theory above (or another mutation theory)A large portion of the populace became infected and mutated; they reverted to a feral state and essentially became immortal. They also became infertile. This was enough to cause most humans to lose faith in their own reproductive abilities; hence, the creation of Alpha and the reason the human population is declining: it's a fear-based voluntary extinction.
The "A2M1-4" records Kokone discovers and becomes obsessed about are the A2M1-4 units themselvesNobody said the earlier "Alpha" series units had to be robots. Earlier unit runs could have been trial programming code. Programming code can be expressed in many, many different ways - yes, even audio recorded on a vinyl record. The exact nature or meaning of this coding may be lost forever; the current Alpha robots seem to be the only ones capable of comprehending the audio, and it seems to directly affect their mood. It's possible the A2M program centered around the development of cybernetic emotional skills or thought-process manipulation. It could possibly be a program used to keep Alpha series robots in check to prevent a " The Matrix" or "Terminator"-style robot insurrection. (This would explain their placement early in the "Alpha" sequence; surely, you'd want to have a means to prevent a robot resurrection early on, preferably before the robots are built.) It could even be the programming for a primitive AI encoded onto a vinyl disk. The "M1-4" model numbers may indicate that four such programs were produced, meaning Kokone has located all of them; or it could refer to the number of programming "tracks" each disk contains.
Ayase is wrong: Misago is a feral robot, specifically an early Alpha prototypeIn Chapter 83, "Blue Sound," Sensei talks about the first of the Alpha series robots created. Her description of the robot is overlaid on top of an image of (what is presumed to be) "Director Alpha," but it could just as easily describe Misago. It would explain everything rather conveniently, especially Misago's lack of age. (And of course Misago can survive on fish; Alpha's protein allergy is clearly limited to her). When Ayase stated that Misago predated the invention of sentient robots, he was simply wrong; he never experienced a world without them, so how can he know for sure what existed before them or how long they've been around, especially since the global devastation wiped out much of the human records?
Misago is a HighlanderWhy not? There Can Be Only One!
Misago is not immortal nor a single individual"Misago" rather represents an entire race - let's say of genetically mutated humans, though it could be something else. This race may live underwater or on a small isolated island near shore. Every now and then, some of the girls venture far from their normal hunting grounds and try to approach humans. Children are less likely to be harmful, so the Misago naturally tend to gravitate towards them more; or perhaps the Misago themselves are children. They all look alike because of creative license; in reality, nobody ever gets a good glimpse of them, and therefore no one can tell them apart anyway.
Misago is the fully matured form of the same type of creature as the water god shrine/"mushroom people"The "face" seen on the "water god shrine" is the larval stage. Over time, it will appear more and more human until it eventually leaves as a fully mature Misago. It's possible that this stage takes a long time to gestate. Whether a Misago can live a very long time, or if we've been seeing different Misago as per the above theory, is left open.
The "mushroom people" are Hatsuseno-sensei's creation, and Misago is a prototypeIn chapter 21, When Ayase sees the face of the "water god", it immediately reminds him of Misago; afterwards, he's seen thinking of Hatsuseno-sensei and wondering what he may be up to. What he is "up to" is sowing mushroom people around the country: the creatures are his creation, and Misago is a prototype left behind. And, related to this theory...
The "mushroom people" were created to replace humanity, and the robots will be their mentorsMore and more of the mushroom creatures are popping up, and from everything we know of them, they seem to be maturing slowly: somewhere in the future, they will attain fully human form and begin walking around. We will be gone by then, but the robots will still be around: they'll help the new race get started and pass on our lore and our memories to them. If robots are the "flower of humanity", the mushroom people are meant to be the fruit. The lamptrees and fungoid buildings may have been created for the benefit of the future new race as well.
The "Alpha" series of "robots" are not robots at all, but the fully matured form of the same type of creature as the water god shrine/"mushroom people"The only evidence we've seen that they're "robots" is, they can plug things into their mouths and the humans around them keep insisting they are. (Even a wetware human could plug something into her mouth if she had an outlet for the plug there; it just so happens to be that the tongue, with its direct connection to the brain and large concentration of nerves [taste buds], is a convenient place to put one.) Perhaps the "water god shrine" is the result of some genetics experiment related to the next evolution of humanity; when they fully mature, they are "harvested" and educated, brought up to believe that they're robots. Perhaps the humans believe this will be less of a shock to them than believing that they're weird genetic mutants; just as likely, the humans in on this figure that the locals will accept cute robots but go after mutants with torches and pitchforks. Kokone can't uncover any records of "Alpha" series robots because they never existed. The Misago are Alphas that escaped and went feral before they could be "harvested."
The "Alpha" robots are directly responsible for humanity's post-apocalyptic decline because they compete with human femalesIt's like the episode of Futurama in which Fry tries to date the Lucy Liubot and the Professor shows him the educational video about dating robots. In the manga, most of Kokone's male co-workers are competing for her attention (though Kokone is oblivious to this until one of her female friends points this out to her very late in the manga), and the vast majority of Alpha's customers (who are overwhelmingly male if we only count each customer once) brave the broken trails to Alpha Cafe just to meet her, knowing full well that there's little chance of anything palatable once they get there. In fact, Alpha herself seems to be a major reason the town's still on the map. Perhaps female robots were so successful in competing for human males that the human population began dying out; nobody wanted to bother with fleshbag females anymore. This might reveal a more sinister motive behind their creation, and the reason there are so few male robots: there was a greater demand for female intelligent walking sex dolls than there was for male ones.
Alpha was Dead All AlongExactly What It Says on the Tin: Alpha
Alpha is really Sensei, and the whole thing is a simulationSensei is running a compressed lifetime's worth of simulations in her ongoing AI research from the perspective of an AI interacting with true AI programs (which can range up to absolutely everybody else), simultaneously determining how AI will react differently if it knows it's a robot as opposed to thinking it's human, and how the AIs will react under varying degrees of isolation. There are few robot males because Sensei is testing what would happen with that parameter. There is no explanation for the decline of humanity because it's not needed; just program the parameters and go.
The Alpha robots are so human-like because each one is built around a SparkSensei was able to achieve a breakthrough in cybernetics, not through her own research, but because she stumbled upon the deactivated corpse of Megatron. While she was fiddling around with him, the rest of the Decepticons discovered his location and attempted to rescue him, razing Yokohama in the process. The Autobots came to the rescue, but too late; as compensation, they allowed the humans to copy Autobot sparks to create robots that would help and provide companionship to the remaining humans of Yokohama.
The weird "mushroom people," "mushroom buildings" and "streetlight trees" are all living manifestations of The ForcePerhaps the genetic experiments proposed in one of the theories above was related to midichlorian research - perhaps it was even responsible for creating midiclorians. A lab accident resulted in these midiclorians breaking out; like their real-life counterparts, mitochondrians, they quickly spread and entered into the cellular structures of the local flora. It's even possible that, in large enough concentrations, these midiclorians even created life forms of their own. These new Force-sensitive beings were then imprinted with the memories of all those around them, especially the local human population.
Along those lines, the "Alpha" series of robots became sentient through the Force and are therefore Force-sensitive.Makes sense if they're fully matured "mushroom" beings like one of the above theories states; but even if they are robots after all, Obi-Wan and Yoda did say that the Force is in everything. Who says that robots can't be Force-sensitive?
The "present" Alpha's owner wanted to give to her was not the camera, but KokoneAlpha's owner probably figured out that Alpha would get very lonely after a while, especially since her cafe sees very little actual business. Furthermore, he probably knew Alpha had never met a robot before. In a weird and pacifist The Plan twist, her owner arranged for a courier service to deliver a
The nature of the relationship between Alpha and Kokone is....
Kokone is a well-tempered, patient Psycho Lesbian (and so is Maruko)Or, to put it another way, they're both lesbian Yanderes. Think about it: Kokone seems outright obsessed with Alpha, visiting the cafe as often as she can, always talking about Alpha, and eventually moving in with her. It seems a bit clingy. And, ironically enough, Kokone has a stalker of her own, Maruko. Maruko seems just about as crazy for Kokone as Kokone seems crazy for Alpha; this is perhaps most visibly illustrated when Maruko practically ambushes Kokone, causing Kokone to pull out her gun on Maruko. Yes, Kokone probably pulled out her gun in fear that she was really being ambushed, not knowing it was Maruko, rather than being genuinely afraid that Maruko was finally enacting a dangerous stalker fantasy, but c'mon, what kind of normal person or robot would sneak up on somebody like that?!
At the beginning of the series (and possibly throughout), Alpha was bipolar (manic-depressive) or suicidalAfter possibly many years of being lonely, and with little to no business coming in, Alpha entered into a state of severe manic-depression or bipolarity and contemplated suicide. The scenes near the beginning of the manga's run, in which Alpha is beside herself with a gun on her desk, represent Alpha's contemplation of suicide. Her meeting with Kokone and their friendship "cure" her of this, but she still shows many manic-depressive or bipolar signs in her behavior and interactions with other people. She even contemplates suicide again when she starts shooting a signpost with her gun; she had originally decided to take her own life, but she had a last-minute change of heart and had to justify to herself taking a gun out back with her being alone.
Ashinano Hitoshi pulled a Hideki Anno and Yokohama Kaidashi Kikou is ultimately the product of bipolarism or depressionRelates to the above theory: ultimately, Yokohama Kaidashi Kikou is about Alpha finding meaning in her existence. Alpha is an Author Avatar for Ashinano. The whole work is an allegory for Ashinano's own struggle to find meaning and purpose in his own life.
Maruko is a transgender robot"Maruko" is actually a male name, as Kokone and Maruko herself point out. And she does act and look very tomboyish....
Maruko was once a slaveThis is why she refuses to take on the family name of her former owners and why she insists on being so "independent."
The reason there are so few male robots is that most robots chose to be femaleRobots are allowed to choose their own gender; most of them, for whatever reason, just prefer being female.
A key figure in the past of YKK is Grant Imahara.The WMG page for MythBusters states that Grant will be an activist for "robosexual rights." Hmmmm....
The reason Alpha and Kokone have handguns for self-protection is that they need the self-protectionPast experience, whether through their own experience or from lessons learned through the interactions of older robot models, have probably told Alpha and Kokone that female robots are frequent targets of rapists and stalkers (which is odd, because most science fiction tells us humanoid robots will automatically have the strength of ten men regardless of the robot's sex or gender). Hence Kokone's reaction when Maruko "ambushes" her.
Alpha is Yotsuba. See that WMG on the Yotsuba&! page for more details (though it ain't much, and maybe just as well).
Yokohama Kaidashi Kikou and Courage the Cowardly Dog take place in the same universeCourage The Cowardly Dog is about how the people of Middle of Nowhere, Kansas (all two of them) cope with life after the same global disaster shown in YKK. The world of CtCD has shown us that they do possess a highly advanced understanding of robotics - a random Chinese tourist was able to build a "better robot dog" that showed a high degree of advancement. The weird events and creatures that happen to Muriel and Eustis are manifestations of the same phenomenon that created all the "weird stuff" in Yokohama - only, instead of imitating the shapes of buildings, people and lamp poles, they try to kill everything. They do say After the End tends to be harsher and more "Bad Ass" in the U.S. than other parts of the world.
[[Video Game/Portal}} Aperture Scienceis responsible for developing the "Alpha" robot series; "A1M1" is GLaDOS]] GLaDOS was abandoned in the Aperture Science Enrichment Center when she began to develop a personality and the ability to express emotions (and began to turn psycho). The guys over at Aperture started poring over any information they could find to figure out what went wrong; one of them did, figured out how to replicate the coding that gave GLaDOS a personality, and modified it so that it wouldn't be so prone to lapse into psychotic episodes. They then sold this technology in order to recoup their losses from the portal gun project, which had been left abandoned in the Enrichment Center (if it was not smuggled out).
The global disaster in YKK is, in fact, the "Seven Hour War" and the Combine invasion.The human population is slowly disappearing because it's being harvested by the Overwatch. A reproductive repression field also blankets Yokohama, but nobody's aware of it. The Overwatch consider Yokohama to be too sparsely populated to post soldiers there; but, had Alpha continued her journey to the most populated parts of Japan, she may very well have run into Metrocops. The Director robot and the Tarpon spend so much time over the skies of Yokohama because the Combine's presence is the least visible there and, therefore, she has the least chance of being intercepted and shot down.
Yokohama Kaidashi Kikou takes place during or after the Eugenics Wars/WWIIIJapan was caught in the crossfire between Khan and his foes, resulting in the destruction and rising sea level seen in the manga. The "Alpha" series of robots were developed in reply to Khan's eugenically modified forces. Humanity does eventually recover though, for some reason, the technology behind the "Alpha" series is lost...until one day, when Arik Soong digs through some ancient records and finds some old, mysteriously labeled vinyl disks, and wills them off to his grandson Noonien....
Humanity bounces back in the endIt seems as if there's a general consensus that humanity eventually dies off in the end even though there's not a lot of evidence corroborating this. Director Alpha notes that the populations are shrinking, and humans factor less and less as the series goes on, but humans are still present throughout the series to the very end. In the last few chapters, Kokone visits what appears to be a rather busy (if not outright bustling) city, and the very last character to appear in the series is a female human - one who hadn't seen birth until nearly the very end of the series, no less.
A major theme of YKK is unrequited loveAll the credit needs to go to a poster at Yokohama Kaidashi Kikou @ pander.us. Said poster pointed out that Alpha seemed to be most attracted to Ayase, who only encountered her twice. Alpha was also highly interested in Nai, but she didn't even leave Kokone a note when she left wandering about. Therefore, the relationship between Kokone and Alpha might be entirely one-sided. In the meantime, Maruko's relationship with Kokone is blocked by Alpha. Sensei and Ojisan, despite having spent their youths together, admit that they've spent their lives alone.
Yokohama Kaidashi Kikou is a pre-history of Battlestar Galactica (2003 specifically)Doesn't take much of an imagination to imagine that most of the human population have gone off-world to establish new colonies, leaving Earth in the hands of the Alphas and their descendants, the Cylons.
Alpha is a robotic trust fund baby, or her Owner is her sugar daddyAnother theory from Yokohama Kaidashi Kikou @ pander.us. For someone who makes little to no money (she's never once seen even handling money), she sure seems to get by. Nobody has caught on because her Owner instructed her to be discreet with their fortune.
The "Alpha" robots are destined to die off soon after humanityYet another theory brought up at Yokohama Kaidashi Kikou @ pander.us, though really this should be evident to anyone putting enough thought into it. Even if their bodies are able to remain functional for thousands of years otherwise, they're still dependent on a fuel source. The question of whether there are enough robots around to maintain a sufficient infrastructure to keep themselves fueled is not answered even though robots seem rare enough such that meeting more than one or two is a seldom occurrence.
Planetarian is a prequel to Yokohama Kaidashi KikouBoth take place After the End, both feature Ridiculously Human Robots that are female, the main characters of both series are learning to cope with loneliness as they wait for their owners, and both main characters develop attachments for those few humans who stick around. Given the circumstances of these works, Planetarian should fit almost seamlessly into the same timeline as Yokohama Kaidashi Kikou, during the final stages of the war that led to humanity's downfall. The Planetarian robot would be an early Alpha-type robot, maybe the same one buried under the grave Kokone ran into before she entered the library.
Most of the humans left Earth for Mars/stars/whateverThe Earth was considered no longer viable, and so they left behind whatever humans wished to stay and some robots to look over the Earth and perhaps one day restore it to its former glory. Hmmmm, kinda sounds familiar....
The "water gods"/"mushroom people" are the graves of deceased robotsYet another theory proposed at Yokohama Kaidashi Kikou @ pander.us. If the robots have any significant organic components in their construction (such as a fungus-like substance), this organic substance can continue to grow and thrive long after the robot itself had died, taking on the shape of its previous form.
Alpha and Nai did itAlpha seemed shyly excited about Nai's, ummm, manhood, and they did spend the night together. We do know that robots can transfer memories by tongue-on-tongue kissing, so it's possible there's memory/sensory transfer during full-blown sexual intercourse. Wouldn't it be ironic if Kokone transferred Alpha's memories to Maruko after they had been transferred from Nai to Alpha during a night of hot steamy robot love-making, rather than Nai's memories directly? (Nai and Kokone had to have had met in order to get the memories in the first place; who knows, maybe Alpha was still there too, and Kokone wouldn't have resisted a quickie from the object of her desire).
Kokone and Nai did itWhy not? If Kokone and Nai met, well...maybe robots have a very loose concept of sexual morality, and maybe only Maruko is the jealous type.
Kokone and Maruko did it (and routinely do it)C'mon, this one's practically Word of God!
I call Poison Oak Epileptic Trees on all WMGs involving Gratuitous Promiscuous Robot Sex.Mainly because the humans appear to have made them as human-like as possible; if this didn't include something as basic as sexual mores, there'd be little point.
YKK doesn't take place in Yokohama, but on an alien world, and the "robots" are plants. The world or humanity isn't diminishing, but rather rebuilding, and everything is in a state of reconstruction rather than decay; plants (Trigun terminology for advanced sentient aliens able to manipulate the laws of physics to their will) are trying to turn the planet Gunsmoke (think Tatooine) into a copy of old Earth. The mushroom buildings and streetlight trees are the visible parts of this process. As for the robots, they themselves are plants who have decided to take human form and intermingle with the humans much as Vash and Knives did; they have either forgotten about their powers or have intentionally kept them hidden.
All the deep meaning and symbolism Ashinano Hitoshi created for Yokohama Kaidashi Kikou is all just accidental and manufactured. According to this site, Yokohama Kaidashi Kikou has a "huge following...in Japan among exhausted salarymen on their way home after a week of 12 hour workdays." Now let's take a look and examine that for a little bit. The stereotypical portrayals in works such as Crayon Shin-Chan and other anime and manga works will do for a starting point. Now, what kind of picture is an exhausted salaryman going to idealize after 12-hour workdays, especially in Japan? Well, first of all, he's probably going to idealize a setting with the absence of monotonous work, probably a setting rich in pretty pasture lands and other rural imagery. Large cities would be banished from this picture because they represent the overcrowded conditions the poor salaryman has to put up with on a daily basis. Now, what else is this tired worker going to idealize, especially when he gets home? A faithful, beautiful woman with a lust for life, (among other things), who nonetheless exerts a healthy independent attitude. (In other words, the exact opposite of Mitzy from Shin-Chan.) Transplant said salaryman's loneliness, urban claustrophobia, and longing to explore unseen lands onto the female character to create an empathetic connection between character and reader, a lesbian element for good measure, and some random elements of mystery with no intended explanation to create a "hook," and you have a surprisingly formulaic, calculated outlook on Yokohama Kaidashi Kikou.
In another part of the world, far away from Yokohama, Blade Runner is happeningYes, yet another Yokohama Kaidashi Kikou @ pander.us transplant theory, basically saying that Blade Runner and Yokohama Kaidashki Kikou are happening in the same universe/timeline concurrently. Yes, that's right, Alpha and the other robots are Replicants, or at least the Japanese version.
In terms of appearance, Alpha (either of them) is a clone of Sensei's younger self (minus the green hair in Miss Hatsuseno's case)They look an awful lot like each other. And green hair dye can't be that hard to find.
The "Alpha" series of robots are Terminators that have lost their memoriesFor whatever reason, they lost their connection to Skynet and forgot who they were, maybe as a result of the war. Therefore, Skynet itself is inadvertently responsible for their lost connection. The local humans aren't aware of Skynet, and so they assume they're just friendly robots. Most of the males, however, retained their connection and are off trying to kill John Connor, going back in time, or both.
Yokohama Kaidashi Kikou is an alternate result of humanity's loss against the Anti-SpiralsLord Genome doesn't exist in this alternate outcome or is killed during the war. The humans return to Earth and set work on the Alpha series of androids, who would continue on the legacy of humanity; they would lack spiral energy so as to not incur the wrath of the Anti-Spirals.
Fallout and YKK are the same universe.No, seriously! The cause of the rising sea levels is global warming; oil has nearly run out, hence the lack of cars and most modern technology; and all the weird creatures are mutants spawned by radiation and genetic experiments (just more... cuddly then what showed up elsewhere). The A7 series of robots were designed to endure the war and help humans rebuild after it by living long and thus retaining knowledge from before. The US did much the same thing except, instead of making cute robot women, they went with a central robot brain that controlled drones, which proceeded to go homicidal after the endâ€¦ oops. Likewise, instead of building vaults like the US, the Japanese opted to produce nuclear powered flying machines to carry key people through the nuclear war and winter. Sadly, much like the US, this proved largely for naught, as most of these preparations failed and much knowledge was lost; luckily for Japan, though, it wasn't nearly as big a target as the US, and so some areas escaped largely unharmed (like, say, certain small out-of-the-way peninsulas). Also luckily for Japan, it didn't have more guns then people, and the slightly less harsh conditions fostered unity instead of a battle for survival, explaining its comparatively better state. Unfortunately, the residual radiation has still rendered most people infertile, and the population is slowly dying off all the same.
The YKK world has moved on.All throughout the story, we get visions of slow decay, of civilisation and genetics starting to run wild, humanity in its twilight, and the traditional concepts of time and space growing fluid as the linearity of time breaks down and turns into a kind of timelessness. The surviving people look back on the past with a nostalgic feeling. Robots, some still faithful to their human masters, are all that remain of the splendid civilisations that came before. All of this points clearly to the fact that "the world has moved on".
YKK shows everyday life in the aftermath of the Singularity.I don't know how else to reconcile the preposterously advanced technology that produced Alpha and the other robots, while people are still relying on piston-engine airplanes, other than that the acceleration of technological change until civilization is transformed into something unknowable has already happened, everyone went off to wherever civiizations go when that happens, and everything afterwards is just the people who were in the bathroom, or not online, or just scratched their heads and said "I don't get it," at some critical moment, and stuff left lying around by accident.
Scooters are vibratorsLooky
Simplest explanation is bestIn the real world, birth rates in most developed countries are already below replacement, and Japan may already be shrinking in population. In YKK, this continues, with ecological collapse being helpful but unnecessary. The possibility of creating human-equivalent robots also helps: given a choice of creating a mortal human child or an ageless and indefinitely repairable robot, most people choose not to have kids doomed to die. Robots are replacing humans, though not necessarily in the same numbers, or in the same places; never fear, the factories and civilization are being maintained somewhere. Yokohama (not to mention Alpha's location) is deliberately a soft decay zone; elsewhere you have higher concentrations of robots and people, not to mention cell phones/Internet. All the biological weirdness is deliberate artistic engineering. I can't explain the never-landing plane, though. Eccentric with nuclear powered plane? Feels more arbitrary than making people-mushrooms.
YKK takes place in Shadow Mirror universe.Alpha and Kokone is very similiar to a W series as they ridiculously look and act like a human ( also, they have same hair colour as Lamia Loveless and Echidna Iisaki respectively ). it's possible that the Great flood is actually caused by Beowulf and Mr Hatsuseno might acquire Alpha from Lemon Browning or rather Mr Hatsuseno is Lemon's fake identity.