The lush visual beauty of the ARIA Anime adaptation is attributed to the animators actually having gone to Venice to do research on the architecture, how Gondoliers pilot their boats and how water moves in reaction to a gondola's oar. Yes, they put that much love into producing the series.
Every building featured is drawn as accurate as possible and the geography is also highly accurate. The location Orange Planet is fictional, though, and ARIA Company is actually in where a Traghetto station would be, and that the walkway behind it in real Venice is way wider.
Berserk surprisingly shows signs of either knowledge or research on Kentaro Muira's part, though this is downplayed between the horrific demons Guts faces and the truly insane amount of megaviolence the manga has. The weapons and tactics used by the warring factions early on (cheap plate armor for mercenaries, heavy plate for knights, cannon for support, crossbows supplanting longbows) is spot-on for 15th Century Europe, and later on the period dress a few of the characters are seen to wear are equally detailed and researched
Detective Conan is chock full of this in pretty much every arc, to the point where some arcs are clearly just excuses for for Conan to elaborate on the chosen factoid of the month. Unfortunately, this tends to make it more obvious when the author does not do the research or uses armchair or fridge logic.
Although much of the bread featured in Yakitate!! Japan is extreme in nature, many breads are, in fact, based on real life recipes developed by the manga's baking consultant. Some of the recipes are featured on the live-action "do it yourself" snippets that appear between certain episodes of the anime.
The author and other creators of Hellsing managed to depict Protestantism, Catholicism, western cultures, vampire mythology, military structure, and accents (Scottish, Italian, British, etc.) far more accurately than 99% of other anime/manga series with eastern roots. It's one of the few animes that averts Anime Catholicism, instead planting the series solidly into the category of Fantastic Catholicism, which is quite common in Hollywood and much more palatable to western audiences. A great deal of conflict is shown between the Protestant Hellsing and the Catholic Iscariot Organizations, including the territorial disputes over Northern Ireland and the hierarchical structure, administration, and international prominence of both religious branches.
Even the slang and insults are fairly accurate to the time period, religions, and nationality of the characters. References are often made to the hostility between two or more specific groups, and women are consistently portrayed in powerful or politically influential roles that don't make them subservient to the men around them. For the latter, the countries in which this power-holding occurs is not outside the norm, either.
Serial Experiments Lain actually pauses the action to show off what the creators found about computers and technology. Or, rather, pauses the exposition about computers and technology for some action. Some of the computer screens shown in the show (most notably Lain's dad's computer in the first episode) feature interfaces that bear a striking resemblance to NeXTSTEP, the operating system the first web browser was created on. This fits in nicely with the show's theme of everyone being connected through the Internet.
The major part of the plot is the development of the new "Protocol 7". The specification of the new internet protocol version 6 (IPv6) was released not long before the show aired.
One of the reasons Digimon Tamers stands out from the other Digimon anime series is the sheer quantity of references to real-world computing developments. Examples include ECHELON (one of the SIGINT systems that control information flow on the internet), the Tierra project (an artificial life simulation experiment), and the early Creeper virus (which infected ArpaNet). Its plot neatly grounds itself in reality with the sole exception of the two instances of Minovsky Physics it created (and their consequences). It also features cloud computing, icewalls (instead of the more well known firewall) and a quantum computer in addition to some philosophical concepts like an entelecheia (a catalyst for evolution) and the relativity of good and evil (the importance of the point of view, which leads to a lot of Well-Intentioned Extremist). But what really makes this example stand out is that the writer, Chiaki Konaka (who also wrote the aforementioned Serial Experiments Lain; seriously, this is a guy who knows what he's talking about), set up a Tamersminisite devoted to explaining in great detail the research and thought processes which went into most facets of Tamers.
The broader Digimon canon as a whole actually does an excellent job of showing its work when it comes to basing its Mons on Many real mythological entities, literary works, religious concepts or even specific lifeforms. Sure, Rule of Cool is in play first and foremost, but they do like to pick pretty obscure stuff to portray and usually do a great job of accuracy in deriving aspects for it; sometimes they even play with multiple Digimon based on different interpretations and views of the same subject (there are plenty of Digimon based on Satan, for instance, exploring different portrayals of him from over the years). Now keep in mind, we're talking thousands of Digimon species, so that's a hell of a lot of work. And of course, though it's rare that much of the details come to pass as relevant in the anime, manga or games themselves, the Japanese supplementary material simply loves to show off how much work they have to show.
Boy howdy, do the animators of Durarara!!!! demonstrate how much work they did, shown here.
Bartender ends each episode with a live-action demonstration of how to make whatever drink was featured in that episode.
Holyland is a fairly realistic martial arts-based series, and there's a lot of different footnotes about how any used or subverted trope fits in with how martial arts and real punches to the face really works.
Vinland Saga gives an accurate depiction of Viking Age Europe, running the gamut from things like weaponry and armour to subtle things like the cultures and religious interplay between the faiths. It's surprising that a Japanese mangaka can get something right that actual Westerners have been getting so woefully wrong for years.
In Heurika, the mangaka got pretty much everything right about the Second Punic War in Sicily, right down to the armor, and the reconstructions of Archimedes' defense machines.
Except the part where it's debatable whether Archimedes really did defend Syracuse with elaborate war machines, and, barring that, the machines depicted in the manga are highly speculative, considering that there is very little real information about the battle.
Desert Punk has accurate depictions of real guns, and a highly varied selection of guns in the series. The author dedicates the end of each Volume to giving the names and specs of the guns used in the series. He focuses on functional guns that would work well in the desert, as opposed to powerhouse guns that would be less reliable in harsh conditions.
Strike Witches Despite being a show about 13-20 year old girls in panties fighting an evil alien threat, many WWII references were made in both moefied and non moefied ways. Erica Hartmann herself is a walking (slightly exaggerated) Historical In-Joke.
Yokohama Kaidashi Kikou is very well researched at least in terms of its geography right down to the specific building depicted as Cafe Alpha having been located right where the manga said it would be. It is a private home in real life. The author comes from Yokohama.
Sailor Moon accurately represents Tokyo, in particular Minato ward. One book details over two dozen locations in the series and their real-life parallels.
Historie has erudite references to Ancient Greek history, culture, literature, economy, geography and warfare. Even the main character is an obscure historical figure. It's not everyday you get Iphricates or Xenophon's Anabasis mentioned in a manga.
Axis Powers Hetalia. Since it's heavily based on world history and all the characters are gijinka countries, it'd be disastrous if the author skimped on research. He even gives an entire bibliography to show his work.
Still, he did overlook more than one detail so the Refuge in Audacity didn't take a turn for the worse. See the main Hetalia entry.
Noir received a lot of attention for its guns, which were all painstakingly detailed drawings of real guns that even all carried the proper amount of ammunition; whenever a scene called for a gun to fire more bullets than it could carry, the animators always put in a shot of the character reloading. The various real life locations on the show — Paris, St Petersburg, New Jersey, and Sicily are also quite detailed and realistic.
In High School Of The Dead, the rifles are amazingly detailed, and are shown to have actual limitations. Kohta Hirano also makes sure that everyone who even touches one follows strict gun safety, as American gun enthusiasts are generally taught to do. The author also shows a decent understand of how the American government works, although it's a bit more subtle and avoids crossing into Strawman Political territory.
The producers of the Gunsmith Cats OVA actually went to Chicago to study it and ensure that their locations would be accurate in the anime. Many Chicago anime fans have noted that the amount of detail to buildings and locations in the anime were so accurate and detailed, they could tell exactly when and where some events took place. This extended to the firearms and vehicles, behaving exactly as they would in real life.
Mahou Sensei Negima! (the manga) has mages casting their spells by chanting in Ancient Greek, Latin, and Sanskrit. Most of which are entirely correct and are full of references to mythological figures related to those cultures. The compiled volumes (at least the English ones) each have several pages dedicated to explaining in detail the languages used, as well as the etymology and mythology related to the names that are mentioned.
It goes into a ludicrous amount of detail concerning the backgrounds, almost all of which are inspired by real world architecture. For instance, they created a complex CG model of a tower in Kyoto for the relevant arc. Said tower appears a total of 2 or 3 times in the background. For another example, one of the bell towers at Mahora is based off of the bell tower of the Florence Cathedral.
Then there's the time Rakan destroyed an entire dimension, and the volume's bonus material spends several pages explaining how the differences between Newtonian and Einsteinian conceptions of gravity and the nature of black holes made this possible.
Played for Laughs at some points, such as a lovingly detailed description of Takahata's car, which appears in a single panel. Or the infamous "Skinship Chapter" late in the series, in which the bonus material describes for several pages the symbolism of the female breast in various cultures (written as though by the groper in the chapter).
Rumiko Takahashi's research of martial arts shows through in Ranma 1/2, to the point where real-life practitioners of these can identify the styles used by the characters right down to the school. Even the anime had a slight concession —the motions that female Ranma, and then Akane, Genma, and male Ranma perform in the first opening animation? Yang-style Taijiquan, form 24. All this in the series that definedMartial Arts and Crafts.
Planetes, both in its original and animated incarnations, is nothing if not accurate to an astronomical degree, up to and including the diaper-clad astronauts. NASA itself has plenty of Planetes fans among its ranks. Rumor has it that if someone actually built the Toy Box (the orbital garbage truck the characters use) as it appears in the source material and somehow got it into space it would work exactly like it should.
One Piece creator Eiichiro Oda frequently makes use of real-life phenomena in the manga, though he will occasionally play with whatever idea he's using and Shonen it up, so it doesn't match completely all the time. Some examples include the Going Merry acquiring a Klabautermann spirit, and the real-life phenomenon of the Brocken spectre, gigantic shadows being cast by people standing at high altitudes. Also noticeable are details concerning sailing, from how weather phenomena work to how the Marines give a backwards, palm-inward salute to avoid showing superiors tar-stained hands.
Many of the characters are named after real-life pirates, and while the names may seem arbitrary at first glance, there is usually some sort of connection between the characters and their real-life counterparts. X. Drake, for example, is a Marine deserter who is seen as a criminal by the government, but is a hero to pirates and revolutionaries; much like the real Sir Francis Drake was considered a criminal by the Spanish but beloved by people in his native England (since he only went after Spanish ships).
Team Medical Dragon is accurate about its information on health care and the health care system, being made by an actual doctor and medical journalist and supervised by another professional.
Koizumi and Kyon act as the author avatars when it comes to complicated concepts and references. See the Genius Bonus page for more details.
The anime had another bonus, too. The neighborhood Kyon lives in is based on the author's hometown of Nishinomiya Prefecture. Every scene in the anime mirrors an actual location in the prefecture, right down to the look of North High (Nishinomiya Kita High School)...even the station, Nagato's apartment, the familiar café...a fan actually did a comparison once of shots from the real place looking identical to the shots in the anime.
This is actually common in productions by Kyoto Animation beginning with Air. People now look for the neighborhoods used as models in each of their productions.
Sakura Wars repeatedly loves to show its knowledge of history especially in the manga form where among other instances Oogami randomly bumps into the first noble Japanese man to win a Nobel Prize for literature (the reference was eliminated in the Tokyopop translation) and also a real life arms smuggling scandal in Japanese occupied China is mentioned to help develop the villain's backstory. Other examples abound in the games, manga, and stage shows in the franchise, one song in the musical Hanasaku Otome mentions Albert Einstein's visit to Japan in that era and also Frank Lloyd Wrights building of the Imperial Hotel in Tokyo.
Hikaru no Go subverts all the usual foofoorah about superpowered gamers by presenting an incredibly informative depiction of Go. Every important match played in Hikaru no Go is based on a famous game played in real life. A real ranked Go player served as a consultant to the series. The series has even been recommended to people who want to know the process for turning pro in real life. You almost forget that there's a ghost hanging over the protagonist's shoulder.
Monster did a pretty good job averting the Hollywood Atlas with regard to Germany. Most of the non-white people we see besides Tenma are Turkish or Vietnamese (two of the most prominent immigrant populations in Germany), while Tenma's adopted hometown of Dusseldorf has a much higher Japanese population than the rest of the country. And Cologne really is notorious for flooding all the time, so a flood washing out the bodies of some of Johan's unfortunate foster parents is very plausible.
Pokémon's anime is so devoted to their movie settings that they'll send whole teams of animators out on location to places like Spain (for the 10th movie), Greece (for the 12th), and so on. These trips are described in loving detail on their blogs.
In the Pokémon Special manga, the Pokédex displays use the game mechanics, such as the sprites, entries, maps, stat lists, etc. for that extra nostalgic feeling.
The Emerald arc shows that the author is pretty aware of metagaming, because quite frankly, the Battle Frontier is nigh unbeatable without specifically trained Pokémon.
All of Ruby's Pokémon have natures that go best with the Contest segment they're meant for.
In Pokémon: Diamond and Pearl Adventure when Hareta and his friends visit Veilstone City in volume 7, there's a shot as they're approaching the town, the entire city appears EXACTLY as it in Platinum version. Mitsumi had Brown Eyes under most circumstances, but gains Green Eyes when she's a Galactic grunt; as Galactic grunts all look the same, and all have Green Eyes.
Pokémon Zensho is more-or-less Red and Green in manga form. The art style, designs, personalities, and roles from the games are all intact. Satoshi is explicitly stated to be eleven years old, same as his game version (many adaptations go for "ten years old" instead). Several scenes excluded in other adaptations are included, such as getting the Safari Zone guys dentures back and the ghost goggles.
Darker Than Black is really good about its research most of the time, to the point where they copied foreign-language graffiti. They also like Rare Guns. The big exceptions are some of the translations; their gratuitous English can be pretty bad and they managed to mess up a Russian translation of the title at the beginning of the second season (but hey, they corrected it in the next episode!).
Fullmetal Alchemist - Hiromu Arakawa obviously did a lot of research on both alchemy (famous alchemists, theoretical alchemic laws, uses for Philosopher's Stone) and chemistry (human composition, conservation of matter). Any breaks from them seems to be either Rule of Cool, Rule of Funny, or the alchemists in question knowing what they're doing (more so than can be shown with just a few images and some relatively small speech bubbles). All this while being a very well constructed, dramatic, fun, and funny story.
Oddly, in the foreword of the first volume, Arakawa states that she intentionally made her alchemy ridiculous and over-the-top, when in fact it is much more rule-bound and logical than most Shonen equivalents.
And if you are a bit into the Hermetic philosophy (which is the basement of medival alchemy) you REALLY get to see how much research this woman did. (Ouroboros anyone?)
Also the production of the movie shows Munich in lovely, lovely detail... and yet makes major mistakes when it comes to food.
The writers have mentioned that they did quite a bit of research on the historical period being depicted, but that they took some liberties for the sake of plot, which could excuse the food error.
Juushin Enbu, another Hiromu Arakawa work (she's doing the art only), is another case of a lot of research. In this case, visiting Beijing and surrounding areas for closeups on how the architecture looked like and the materials used to make it, as well other cultural aspects of ancient China. She shows the creative team's research trip at the end of each collected volume.
Kamui Den: Surely one of the crowning examples in modern media. The detail in which author Shirato Sampei describes everything from mountain fauna to 17th century taxation can be overwhelming. And there are long sections of expository text that resemble textbook entries.
An all manhwa group created the manga Kurokami. The gorgeous Scenery Porn and the cultural references would never clue you in to the fact nobody on the team ever actually stepped into Japan or could speak the language. (The script was translated in Japan before official release) Omakes in the back show the research process, like when they looked through photographs for the backgrounds. Just out of simple curiosity, they once called the actual building that they were going to draw because they liked the structure, asking what the building's purpose was. That building was a condom factory.
The Baccano! anime has been recognized for being one of the few animes that get American history right. It even went as far as to show "Hollywoodland", which was what Hollywood was called in the 30s, in a montage.
Except of course the fact that soup kitchens serving curry could only happen in a bizarro world.
They got a bit lazy on the names after a point. Prochainezo isn't a name, for one thing, and the diphthong "ch" is pronounced "k" in Italian; it should be spelled Proccenezo. Neither is Nice, Luck, or Jacuzzi Splot. Jacuzzi is a real surname, though (which is probably where the confusion came from. The brand of hot tub is an eponym). But they DID use a very real Polish name: Czeslaw Meyer, which comes with the bonus of being Ambiguously Jewish. The fact that they spelled it right is particularly impressive. They probably got it from famous Polish poet Czeslaw Milosz.
Princess Tutu shows its knowledge of ballet and classical music throughout the series. Ballet scenes based on classical ballets generally take choreography directly from the ballet. The details go down to costumes, dance moves, and pantomime. The show also makes clever use of classical music, such as when it uses the "Blue Danube" waltz in an episode about a river.
In one episode, Rue performs "The Dying Swan".
In Legend of Galactic Heroes the author of the novels shows this through details that emphasize the parallel between the Galactic Empire and the Second Reich/German Empire/Prussia. For example, the Kaiser's palace is Neue Sanssouci, a new version of Sanssouci, the palace belonging to the German Emperors. The animators take it further by including architectural detail such as greatly decorated gazebos, also existing in the actual Sanssouci.
Then we have the myriad historical allegories and parallels. The main one is Reinhard von Lohengramm being a very direct expy of Frederick the Great, in that not only is he a tactical genius, but he also advocates Enlightened Despotism, ie a monarchy informed by enlightenment values of improving society for everyone, not just for the wealthy, encouraging the production of knowledge, fighting unfairly gained privilege and corruption.
Futari Ecchiis a sex-education and relationship advice guide disguised as an ecchi manga - complete with references.
Kaze Hikaru author Taeko Watanabe's talks at the end of the volumes often talk about all the trouble she goes through to do this: from redrawing parts of the manga that were inaccurate due to relying on popular culture or lazy research to changing a famous plotline from the Shinsengumi's history because it couldn't possibly be historically accurate, even though she knew it would disappoint fans.
Ookiku Furikabutte. The author, Asa Higuchi, obviously knows her stuff when it comes to baseball, which makes sense when you consider that she got a major in sports psychology.
More Scenery Porn in Elfen Lied, which takes place in the Kanagawa Prefecture. Each scene looks like a postcard.
The treatment of various transgender issues in Wandering Son: no Easy Sex Changes, being trans as a child, having transgender feelings as a kid but growing out of it, being a fully transitioned adult, sexual orientation in regards to being trans (hint: gay and trans are NOT THE SAME THING and the author seems to understand this), et cetera.
Not to mention Spirited Away where the car at the start and end is a representation of a real car and the studio obtained a car of that make and model then recorded its sounds to use in the film.
Dinosaur King has many very obscure dinosaurs and a wide variety of places are visited. Also, it gives its most of its maniraptorans feathers.
Syun Matsuena puts so many different martial arts and their actual move names into Kenichi: The Mightiest Disciple it's like a whistle-stop tour of martial arts, since Kenichi's masters feel compelled to give the history and characteristics of any art mentioned.
Angel Beats! shows firearms and their real life counterparts very accurately.
Zero no Tsukaima gets a surprising amount of stuff about the Renaissance correct considering how much gets thrown into silly harem antics.
The manga of Gunnm enjoys detailing exactly how all the metals and materials used in making the cyborgs work.
Despite being of separate authors and genres (science fiction horror and action shounen respectively), both Sagusa Yu's Terrafor MARS and Murata Shinya's Arachnid obviously show an intense fascination with the strengths and weaknesses of various real-world insects. In Arachnid's case, this is part of the Insect Motifs related to each of the assassins and their method of killing, including the main character, whose abilities mimic various spiders (hence the title). This is taken more literally in Terra Formars, where the exterminators attempting to kill off the mutated humanoid cockroaches populating Mars inserted themselves with the cells of bugs to combat the hostile man-made aliens. For example, the main character so far, Komachi, gives himself the power of the Asian Giant Hornet when his Berserk Button is pushed.
JoJo's Bizarre Adventure frequently pauses the plot to explain random things in great detail, from the local customs in the place the protagonists are travelling through, to the construction of a villain's favorite guitar and why he bought it.
Ambiguous Disorder may be a common trope, but seldom there is a case like the local Idiot Savant Mashiro from Sakurasou no Pet na Kanojo, where a diagnosis of autism became Word of Dante. Looking at the scarily accurate descriptions of Mashiro's mannerisms, especially on little things like having a flat affect, being incredibly picky about food textures, etc, Hajime Kamoshida must have consulted a standard textbook about the condition.
In the Lupin III movie, The Castle of Cagliostro, by Hayao Miyazaki: Every vehicle or gun seen, even those shown for only split seconds that you have to freeze-frame to see, were either exact replications of real-world items or based on real-world designs.
The depictions of England in the first episode of Kin-iro Mosaic are basically accurate; and the Carteret house was basically drawn out of a real English Bed & Breakfast, with permission. The show for the most part also defied the Gratuitous English trope, by using voice actors with a better grasp of English and hiring an English school to review the scripts.
Suicide Island's author spends many text boxes (and even a page) explaining many things about surviving on an island. Some things unrelated to surviving (what goat meat tastes like) are also mentioned.
Shirokuma Cafe makes numerous references to animal facts and obscure ways to make coffee.
In Attack on Titan, author Hajime Isayama worked with an engineer to design the Three Dimensional Maneuver Gear used to fight the titular Titans, so the physics and mechanics of using such devices are somewhat plausible.
The 25th episode of Steins;Gate has the cast go to Los Angeles complete with very accurate details of the city.