{{Anime}} aired from around 11 p.m. until the wee hours of the morning, occasionally indicated by the odd-looking "22:00-27:00" annotation. They are almost universally watched by an older male audience, and often mocked by any shows aired earlier.

This sounds like a rather strange time to broadcast a show that's trying to make money, but it works for several reasons. These kinds of time slots are usually bought by production companies (generally a span of three months, called a ''cour'') who end up as their own sponsor. This is cheaper than depending on someone else's advertising money. These shows have a strong, if unusual, MerchandiseDriven concept that help pay for themselves. This is supplied by the often small but dutiful fan base. The TV station gets to fill an otherwise crappy time slot.

Unlike the United States, the TV in Japan is still driven heavily by the six free-to-air broadcast networks (like many other large Japanese corporations, they're practically government). Satellite channels exist and do air anime (either first or second run), but they only account for about 10% of overall viewership. This more competitive atmosphere means that very few series can pull the ratings necessary to stay in the lucrative after-school or prime time timeslots.

There is also, like in many other countries, a concern over content; when ''Anime/NeonGenesisEvangelion'' aired in the dinner hour in 1995 to massive numbers of complaints over its sexual and violent content, many networks dropped anime programming from similar timeslots.

This also creates the infamous tendency to neuter, [[CensorSteam literally]] or [[OffModel figuratively]], the broadcast in an effort to get you to buy [=DVDs=]; recent shows may not even supply the 'full' finale. In fact, many small companies don't even release {{OAV}}s anymore unless they've done a TV run, just to make sure their audience wants them. However, how much FanService the show actually provides can vary quite a bit.

Interestingly, distribution in the fansub community largely removes this time restriction, as does DVR technology (which allows people to set their TV to record a show at, say, 3 a.m., and then watch it whenever they like it) and streaming. A [[PeripheryDemographic unexpected demographic can take interest in a show]], or a larger fandom is created for a series that originally had a much smaller one.

See also {{Watershed}}, SafeHarbor.
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!!Examples

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[[folder: Japan]]
* Despite being a {{shoujo}} series, the first season of ''LightNovel/MariaSamaGaMiteru'' aired at OtakuOClock, while the second aired on a more intuitive Sunday morning timeslot. Aside from testing series potential, this was probably a safety device to see [[SubText how far they were allowed to go]] and because the producers are well aware of the net created by its PeripheryDemographic loyalty. After a "third season" of [=OVAs=], the fourth season again aired at OtakuOClock.
* ''SoukouNoStrain'' aired around midnight.
* ''MacrossFrontier'' was aired at 1:25 AM (rendered on Japanese TV as as 25:25) in spite of having a ridiculous amount of mainstream promotion. This is just one small part of the Noachian deluge of "25" references the series made to commemorate the 25th anniversary of ''Macross''.
* ''Anime/MagicalGirlLyricalNanoha'' originally showed somewhere around this time, which, considering the otherwise mostly tame content of the show, is the main clue it wasn't originally marketed for little girls.
* ''InvisibleGirlEa'' (Toumei Shoujo Ea) was shown during this timeslot, although it is a live action series (but based on a game).
* ''Anime/CodeGeass''' first season aired at 12:30, which apparently allowed them to get away with bloody violence, swearing, [[spoiler:a girl masturbating with a table corner, and the massacre of a stadium full of people.]] The fact that the second season aired at 6 PM on Sunday, a timeslot typically reserved for news programming, required them to drastically alter the plot.
* ''Manga/HayateTheCombatButler'''s first season was on a Sunday morning kids' show time slot, but the second season moved here. Perhaps because of all the references and otaku nature of the show.
* ''Anime/LastExile'' was broadcast at around 1:00 AM during its first run in Japan.
* In ''Manga/LuckyStar'', Konata is known to lament the fact that shows airing in this slot on normal channels often don't air at all when sports broadcasts run long, in addition to shows airing earlier being bumped into it temporarily.
* ''Anime/SerialExperimentsLain'' aired at 1:15 AM, which in 1999 was one of the earliest attempts at broadcasting anime in this timeslot.
* According to the Japanese commercials, ''Anime/GunXSword'' appeared at 1:30 AM. Despite this, American audiences frequently tag it as a shonen series.
* The second season of ''Manga/TheWorldGodOnlyKnows'' airs around 1 AM or so.
* ''VisualNovel/UminekoNoNakuKoroNi'' got this sort of time slot when it came out.
* Some {{Toku}} and {{Dorama}} programs that are most definitely not for younger audiences also aired during Otaku O'Clock:
** ''Series/{{GARO}}'' came on at 1:30 AM, its two-part made-for-TV movie was on at midnight, and [[Series/GAROTheOneWhoShinesInTheDarkness its sequel series]] aired at 1:45 AM. Given that it's a horror series, its late-night timeslot is thematically appropriate too.
** ''CuteyHoneyTheLive'' had a 1:00 AM broadcast time.
** ''Series/UltraSevenX'' was aired at 2:15am on CBC and 2:25am on Creator/TokyoBroadcastingSystem.
** ''Literature/DeepLove'' was shown at "25,30" due to the fact the main character is a prostitute and the audience gets to see her at work.
** ''TheAncientDogooGirl'' was on at 1:25 AM and its ''Dogoon V'' sequel was on at 1:35 AM.
** ''Series/HikoninSentaiAkibaranger'', airs at 1 am and 1:30 am on BS Asahi and TOKYO MX, respectively.
* In Japan, ''Manga/JoJosBizarreAdventure'' is one of the absolute pinnacles of {{Shounen}} anime. But due to how violent it is, the 2012 TV anime adaptation is aired at 12:30 AM.

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[[folder: Other]]
* An early version of Otaku O' Clock relates to different reasons in the years before anime was mainstream in the US. During its initial 1985-1986 runs, ''Anime/{{Robotech}}'' was shown mostly during the early hours of the morning such as 6:30 or 7:00 am, alond with many other syndicated import shows. This was believed to be due to the tendency for parents to still be asleep and unaware of the mature content of what was supposed to be "just a cartoon". It should be noted that ''Robotech'' was originally broadcast on NBC affliates before their SaturdayMorningCartoon lineup, which at the time usually began around 8:00 am. At that time, NBC broadcast an annual primetime preview special giving glimpses into the season's soon-to-start Saturday Morning Cartoon lineup, particularly highlighting new cartoons. Robotech was not mentioned in the fall 1985 special.
* In Australia, anime is most prevalent on public children's channel Creator/{{ABC3}} where it airs in a block at the latest point on the channel's run on Saturday (''Anime/AstroBoy'', ''Anime/DeltoraQuest'', ''Manga/FruitsBasket'', and other kids shows). Being a children's channel, however, [=ABC3=] stops at 9pm. Otherwise, anime airs at either seven in the morning on a commercial channel (''Franchise/YuGiOh'', ''Anime/{{Pokemon}}'', ''Franchise/{{Digimon}}'' and other kids' programs) or around midnight on the multicultural channel {{SBS}} (the collected works of Creator/HayaoMiyazaki, ''Anime/GhostInTheShell'' and so forth).
* ''[[Franchise/DotHack .hack//Roots]]'' on Creator/CartoonNetwork fits (or rather, used to fit) this bill, airing pretty close to midnight -- though only on one day of the week (Friday), and it eventually got, of course, ScrewedByTheNetwork in the middle of the latter half of the anime. It was moved to 4:30 AM EST without any warning or advertisement. It would eventually finish airing in it's entirety, but the final few episodes were deliberately put on hiatus for a few weeks to coincide with the release of the first VideoGame/DotHackGU game due to spoilers involved in the plot.
* The short-lived UK channel Anime Central nearer the end of its life consisted of a two-hour block on another channel by the same owners, starting at about 1 AM- on the site for the audience ratings board in the UK (BARB), showings were referred to as "25:00".
* The SciFiChannel's Ani-Monday block ran from 10PM to 12PM EST. They adjusted it for time zones for the standard channel but not the HD channel, so on the west coast you could see it at 7PM, potentially averting the trope.
** It was relocated to Tuesdays in January 2011.
* Logo's "Alien Boot Camp". The website helpfully calls it "where LGBT [[OtakuOClock fans of video games, sci-fi, comics, horror and cool techie stuff]] collide".
* This is the theory behind Creator/AdultSwim, which airs between 9 PM and 6 AM and devotes its Saturday night broadcast to anime.
** They've started a new segment called "DVR Theater" which shows some of the older CultClassic programs around 4:00 AM.
** And the revived form of Creator/{{Toonami}} now takes the place of the anime block on Adult Swim, running from 11:30 PM to 6:00 AM on Saturday night.

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[[folder: Fictional Works]]
* In [[Webcomic/ChibiMikuSan Vocalotown]], ''Anime/BlackRockShooter'' [[http://danbooru.donmai.us/post/show/412022 aired at "25:30"]] (the real BRS anime ended up airing at 24:45).
* An in-universe example occurs in ''Manga/{{Bakuman}}''. The anime adaptation of the ''Magazine/ShonenJump'''s ''Otters 11'' is aired at midnight due to the nature of its content. Its brand of serious humor seems cater more toward an older PeripheryDemographic than to Jump's younger audience.
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