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

This is common in Japan for several reasons, even if it seems like a weird time to broadcast a show that's trying to make money.
* These shows tend to have a strong (if unusual) MerchandiseDriven bent, which allows them to pay for themselves; this means that production companies can buy these timeslots directly from the networks and sponsor their own shows. The [[{{Otaku}} fan base tends to be small, but dedicated]], so it's usually worthwhile to do this.
* Most TV in Japan is provided by the six free-to-air broadcast networks[[note]]Or independent broadcast stations which are members of the [[https://en.wikipedia.org/wiki/Japanese_Association_of_Independent_Television_Stations JAITS]] [[/note]] (which, like many other large Japanese corporations, are practically government). If it's not on one of those networks, it's not likely to succeed, and because the landscape is so competitive, very few shows can draw the ratings needed to stay in prime time or on an after-school timeslot. Shows aired on cable or satellite channels account for only 10% of overall anime viewership in Japan.
* Content concerns are a big deal, as in most other countries. Otaku O'Clock shows tend to be on the more violent or sexual side in terms of content. Such shows have been aired in prime time before, but not to universal acclaim; in particular, there was large public outcry in 1995 when ''Anime/NeonGenesisEvangelion'' aired in the dinner hour. In spite of the post-{{Watershed}} timing, though, many of these shows will still be {{censor|shiptropes}}ed or [[OffModel otherwise poorly executed]], at least partly [[MoneyDearBoy to convince the otaku to buy the DVD/Blu-Ray]].
* And in this era of [=DVR=] technology, it doesn't really matter when you air the program anyway; the fans will record it or stream it. Where the show isn't aired, {{fansub}}s will provide the show.

The trope name refers to the odd way of noting when the shows start airing; it's common to see a show aired at 1:00 am listed at "25:00". This is largely done to align the schedule with that of the previous day; many Japanese TV networks still sign off in the middle of the night, and those who don't will only switch to "the next day"'s programming at 4 am or so.

See also {{Watershed}}, UsefulNotes/SafeHarbor.


[[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.
* ''Anime/StrainStrategicArmoredInfantry'' aired around midnight.
* ''Anime/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 ''Anime/{{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.
* ''Series/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 25:25 (1:25 AM), which apparently allowed them to get away with [[FamilyUnfriendlyDeath bloody]] [[FamilyUnfriendlyDeath violence]], swearing, [[spoiler:a girl [[ADateWithRosiePalms masturbating]] with a table corner, and the massacre of a stadium full of people]]. The fact that the second season aired at 5 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. Coincidentally, much of this anime takes place at night or in otherwise surreal circumstances, so the decision to air it at night may have been to enhance the viewing experience. That and the fact that it StartsWithASuicide.
* 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'' aired around 1 AM or so.
* ''VisualNovel/UminekoWhenTheyCry'' got this sort of time slot when it came out.
* ''Manga/AttackOnTitan'' first aired on at 1:58am on MBS. Creator/{{Toonami}} aired the dub at 11:30pm, which is close enough to the trope.
* 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.
** ''Series/CuteyHoneyTheLive'' had a 1:00 AM broadcast time.
** ''Series/UltraQDarkFantasy'' was aired at 1:00am on Creator/TVTokyo.
** ''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.
** ''Series/LionMaruG'' for the same reasons as Deep Love and it is also aired at 1:30 AM.
** ''The Ancient Dogoo Girl'' was on at 1:25 AM and its ''Dogoon V'' sequel was on at 1:35 AM.
** Both seasons of ''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.
** Oddly enough, ''Anime/HunterXHunter'' (The 2011 version) oddly enough started airing at ''10:55 AM'' on Sunday morning, despite being one of the most violent mainstream {{Shounen}} manga out there. [[{{Bowdlerize}} It was still quite censored]], but it was still quite violent for its timeslot, hence moving to Tuesday Nights 25:30/Wednesday Mornings 1:30 AM for the last portion.
* ''Anime/Persona4GoldenTheAnimation'' got amazingly dead time slots after 1:30 AM on both channels it aired on, due to being an expansion on the original ''Anime/Persona4TheAnimation'', that only fans of the original show or the games would understand and want to see.
* ''Anime/SandsOfDestruction'' was originally created to promote [[VideoGame/SandsOfDestruction the game]], but was aired at midnight and 1 AM, casting doubts on how much "promotion" it actually accomplished. The game was only rated B (12+) by CERO, and the show itself is ''incredibly'' tame, no more violent than your average afternoon {{Shounen}}, with no foul language or sexual content. There ''is'' the little matter that the show's "heroine" claims to be out to destroy the world, but half the time they don't even ''mention'' that fact...
* The first season of ''Manga/{{Haikyuu}}'' aired on Sundays at 5 PM. The second season, however, moved to the Saturday late-night time slot.
* Despite being a Shonen Jump series, ''Manga/ShokugekiNoSoma'' was determined to be too risque for a daytime slot, therefore aired at 2:30am on MBS.
* ''Anime/OsomatsuSan'' aired at 1:30 AM time slot.
* ''Anime/{{Nightwalker}}'' was part of the early wave of late-night shows in the late 1990s, and aired at 1:45 AM.
* ''Anime/LittleWitchAcademia'' airs at 12:00 AM time slots. Many people questioned why due to its kid friendly content until the [[DarkerAndEdgier second cour]] from Episode 15 onwards which included more swearing, HeroicBSOD and a [[ArsonMurderAndJaywalking living nuke trying to destroy the world]]. The reason why it was aired at 12:00 AM was because it had no other timeslot to air.

[[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, along 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 affiliates 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 Creator/{{SBS}} (the collected works of Creator/HayaoMiyazaki, ''Anime/GhostInTheShell'' and so forth).
* ''[[Franchise/DotHack .hack//Roots]]'' on Creator/CartoonNetwork 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 its 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.
** This actually happened to [[ScrewedByTheNetwork quite a few Anime]] that tanked in ratings. ''Manga/YuYuHakusho'', ''[[Anime/ZoidsChaoticCentury Zoids: Guardian Force]]'', ''Anime/IGPXImmortalGrandPrix'', and ''Manga/DotHackLegendOfTheTwilight'' all got similar treatment.
* Near the end of its life, the short-lived UK channel Anime Central 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 [[Creator/{{Syfy}} Sci Fi Channel]]'s Ani-Monday block ran from 10PM to midnight Eastern time. 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 fans of video games, sci-fi, comics, horror and cool techie stuff collide".
* This is the theory behind Creator/AdultSwim, which broadcasts nightly from 8 PM and 6 AM and devotes Saturday nights to anime.
** [as]'s "DVR Theater" segment showed some older CultClassic programs around 4:00 AM.
** And their revival of Creator/{{Toonami}} took the place of their own anime block.
* During the years when being a ''Series/DoctorWho'' fan meant you were an anorak of colossal proportions, the ''AudioPlay/BigFinishDoctorWho'' audio dramas were played on Radio 4 at painful hours of the night (and in the years before iPlayer and Listen Again made this less important) - especially cruel seeing as they were still, essentially, children's programmes. As the revival series started and the show's profile improved, the BBC gave it more sympathetic time slots - in particular, broadcasting the first season of the ''Fourth Doctor Adventures'' in the traditional Fourth Doctor-era time slot of 5:15PM on Saturday.
* The children's network ''Qubo'' had a block called "Qubo Night-Owl," which played episodes of old Filmation cartoons.

[[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.