Japan's version of self publishing or independent press.
While doujinshi is traditionally represented as self-published manga, it literally means "amateur publication" and has come to be used as a synonym for any independently published Fanwork. Doujinshi produced by a team is usually credited as a "doujin circle" rather than an individual's Pen Name.
Notably, doujinshi may feature either completely original content or content derived from an existing intellectual property. Printed doujinshi was traditionally published in limited quantities because of financial limitations. In regards to non-original content, this also assures fans do not step on the toes of the IP's original owners to any large degree, and many companies see amateur work as free promotion. Since doujinshi are also a way of dodging Executive Meddling, doujinshi are less subject to censorship; sexualized and otherwise transgressional depictions are infamous traits of doujinshi, though not actually representative of the whole.
In recent years, there has been an upswing in the activity of both amateur comic artists and professionals wishing to work "outside the system". Concurrent to this has been a support system enabling the production and sale of these works at a scale that few Western artists or writers could accomplish. The biggest semi-annual doujin sale convention, "Comiket" (Comic Market), has an attendance of some 500,000 people over each three-day event. Because of even tighter financial and legal limitations, doujinshi in the West is represented prominently, if not almost exclusively, on the internet.
The second most popular form of doujinshi is video games, often programmed by one person or a very small group. Probably the most well-known of doujin soft producers, and one of the few to cross over into commercial game production, is Type-Moon. The Touhou games constitute possibly the longest-running series of doujin game productions, since the first one was released in 1996 and there have been 19 games in the series, although there are other potential contenders to that throne.
Doujinshi has two effects upon Anime: the first is that several highly regarded anime have been based on either doujinshi or on artists who established their presence as creators of doujinshi. This includes famous individuals such as CLAMP, Ken Akamatsu (who dabbles in both), and Yoshitoshi ABe (who created the original doujinshi that Haibane Renmei is based on).
The second effect is that a number of anime feature doujinshi as either primary Plot Points or sideline elements. Involvement in doujinshi is usually a trait of Otaku Surrogates. Comic Party and Doujin Work are stories centered around it, while Genshiken addresses it as a fandom trait; Otaku no Video from Studio Gainax is essentially a fanciful self-biopic of the company's origins as a doujin circle.
Interestingly, the first doujinshi were made in America during the early 20th century. Called "Tijuana bibles", these were eight-page porn comics usually starring cartoon characters or movie stars having explicit and often-comedic sex (there have been guesses why they were called Tijuana bibles, but the reasoning is always obscure). The creator of Li'l Abner famously said that he knew he'd hit the big time when Tijuana bibles of his characters began to surface. The first "doujinshi" to raise a major fuss was an underground comic called Air Pirates Funnies. After the first issue, the existing designs were replaced with Disney characters in rather explicit situations; naturally, this didn't please the House of Mouse.
Related to the above, doujinshi is not a uniquely Japanese phenomenon. Doujinshi and doujin circles from other nations are not uncommon and even Japanese media refers to them as such.
Technically, it's near-impossible to import doujinshi, and the makers are well aware of this. Nevertheless, there are online stores that carry them with worldwide shipping for dedicated importers and artists (mostly musicians) who offered their work outside of Japan. Also, there exist proxy buyers that one can hire in order to buy everything one wants, given that stores like "Toranoana" or "Melonbooks" can't export overseas.
Regarding translations of those works, some artists don't mind them, as they believe it's an extra-promotion for their works overseas. However, many artists are very worried about the blatant piracy of their works, especially by foreigners (artists from circles like LINDA Project, ARCHIVES and Circle Huan have stated that they don't want their works to be published in websites that people outside of Japan can access), and they have started to take actions against websites and "scanlations" in 2013.
- Harumi Fujiyoshi from Sayonara, Zetsubou-Sensei is, as her name holds true, a Yaoi Fangirl. Naturally, she's into slash and a lot of her drawing material involves Shout Outs and references to other anime, mostly involving material like the above picture.
- When Itoshiki-sensei learns about Fujiyoshi's hobby, he says he put out a few doujinshi in his student days. Naturally, he means self-published literature in a rather old-fashioned format and both characters get the wrong idea about each other's interests.
- In Mahou Sensei Negima!, Haruna writes Doujinshi, although we don't see a lot of her work. There's even a memorable interlude where she drags Negi to a Doujinshi convention, and he unknowingly picks up a yaoi hentai, nearly giving Chisame a coronary. There's a good reason that we don't see a lot of Haruna's work; Word of God is that it's "rated 18+" (let's not forget that Haruna herself is supposed to be no older than 15).
- Konata from Lucky Star is a Comiket veteran, once recruiting her friends to come with her, during which episode, Kagami spots the yaoi doujin of Gauron and Sousuke from Full Metal Panic! pictured above. Curiosity gets the best of her, and...well...hilarity ensues.
- The eponymous club in Genshiken has a locker full of Doujins in the club room. Later, the club produce their own doujinshi for Show Within a Show Kujibiki Unbalance. Oguie also draws yaoi doujinshi, and once accidentally spills a large pile of hardcore ones she bought in front of the boys in the club.
- Nagi of Hayate the Combat Butler draws her own, it's her berserk button if you call it a 'picture diary' (a ubiquitous form of summer homework for Japanese school children). Several chapters of it have featured in the anime and manga. The only one who's able to understand the story is Isumi.
- Doujin Work is, unsurprisingly, about people involved in the doujin manga scene, with varying levels of success. Apparently, one can make quite a profit in making doujinshi, as Justice can attest.
- Comic Party is an anime/manga (based on a dating sim game) about the process of making doujinshi (referred to in the English dub as 'fan comics'). The main character is convinced by a friend of his to use his artistic skills and use doujinshi to "Take over the world." The process of doujinshi is shown in detail, from scripting to printing to selling.
- Hanaukyō Maid Tai La Verite episode 5. Ikuyo Suzuki takes the main characters to Comiket to sell her manga, which (based on its cover) features a (fictional) relationship between the maids Yashima Sanae and Konoe Tsurugi.
- Visionary Replay Of Homu Homu, a sexually explicit Puella Magi Madoka Magica Homura/Madoka Girls Love story.
- The character designer of Madoka Magica, Ume Aoki, makes doujinshi under the pseudonym Apricot+; a Madoka doujin is among the works she made under this name.
- Mobile Suit Gundam Wing: Ground Zero, which actually got published in the US through Viz, and can be distinguished from the official manga by the fact that it doesn't have any of the show's staff in its credits (and because it conflicts with manga that do like Blind Target).
- Nakuru from Mayo Chiki! is one. She's obsessed with making BL manga, particularly after seeing the butler for a local rich girl, Konoe Subaru hanging out a lot with Ordinary High-School Student Jiro.
- Chihaya from Samurai Harem: Asu no Yoichi is another in-universe example. She draws manga and goes to school, but sometimes has trouble trying to fit both into her life. When some of her classmates belittle her efforts, Yoichi beats them up and also chastises them since they lack motivation to do anything themselves but are quick to criticize others for trying to make something of their life. Which then gives Chihaya some more ideas for her manga.
- Morefuyu is based on Morenatsu, but taking place in winter instead of summer.
- Episode three of Humanity Has Declined is an extended parody of the concept. Entirely using yaoi fangirls.
- In Oreimo, the main character, his sister and two of her friends go to Comiket for doujinshi early in the series.
- Haiyore! Nyarko-san's second season opens with Mahiro discovering that there's a doujinshi about him — and naturally, to his abject horror, it's Yaoi. He ends up buying it just so he can burn it and keep it out of the hands of his Unwanted Harem. The doujin's author Tsuruko is a star-struck Yaoi Fangirl of Mahiro's and spends the entire season trying to meet him, imagining how wonderful it'll be (never realizing that his reaction could be anything except joy).
- In The Rising of the Shield Hero Motoyasu displays surprising skill making doujin after he goes insane. His work is very popular with the citizens who have never seen that type of work, though Naofumi is squicked over the main focus of the erotic works being Firo.
- Miki from I Can't Understand What My Husband is Saying is part of a doujin circle called "Fate Deniers" that specializes in writing good endings for series that had Downer Endings; even his username is called "Destiny Fucker". Meanwhile, Youta "Mayotama" Tsunashi draws Yaoi doujinshi based off of fantasies he's had of his brother. In a case of Reality Ensues, knowing he can't earn as much on amateur works, he decides to switch over to Shounen in an attempt to get his work professionally published.
- Fafnir from Miss Kobayashi's Dragon Maid starts selling manga at Comiket after he gets into anime. Only a single person buys his work (and said person was his roommate). Said roommate, Matoko Takiya, is part of a popular doujin circle (he also programs his own Bullet Hell Doujin Soft in the anime).
- Watchmen includes Tijuana bibles as a minor plot device.
- Doujin works in this format have a tendency to be created as fighting games, usually emulating the style of Guilty Gear:
- Azumanga Fighter
- Battle Moon Wars
- Big Bang Beat
- Eternal Fighter Zero
- Immaterial and Missing Power, Scarlet Weather Rhapsody, and Unthinkable Natural Law are all fighting games as opposed to the series' usual shmup style. All three, however, are also canon.
- Valkyrie Fight
- Pokémon Type Wild
- Magical Battle Arena
- Melty Blood
- The plot of this one, however, is considered canon in some ways.
- The Queen Of Heart
- When They Cry
- Doujin shmups are also quite big:
- Doujin action titles are notable as well:
- Yume Nikki, which later got its own manga series
- Pintsize inverts the stereotype.
- In Ghastly's Ghastly Comic, Freddy draws doujinshi based on Chick Tracts, and after Cosplay Girl converts to Buddhism, she draws a Bishōnen Buddha/Drunk And Bitter Jesus doujinshi (with Jesus as Seme). Bishonen Buddha then reccomends she start worshippping Fat Buddha instead.
"He's Japanese, you know. You kids love that crazy Japanese stuff, right?"