History OOCIsSeriousBusiness / AnimeAndManga

* ''Anime/YuGiOh'' has one which comes after that duel when Yami played the Seal of Orichalcos simply because he couldn't stand the thought of him losing and it caused Yugi to lose his soul. After a [[MyGodWhatHaveIDone guilt-ridden]] Yami arrives at a mystical place where he can make contact with Yugi, who gives him an epic TheReasonYouSuckSpeech before challenging him to a duel in which he uses the Seal of Orichalcos against Yami. It turns out to be a CruelToBeKind situation, where Yugi lets himself become the darkness that Yami must defeat in order to move forward, but still...

* ''Manga/BlackClover'': In "Two New Stars", when it's revealed that the [[IdiotHero Black]] [[RagtagBunchOfMisfits Bulls]] have come in second place at the Star Festival -- after only [[TheAce the Golden Dawn]] -- ''everyone'' is in complete disbelief, even the Black Bulls themselves, who were all convinced that they would come in dead last. It's shocking enough that Gordon, a Black Bull member who always mutters so softly that the audience can only understand him thanks to subtitles, says out loud ''without'' subtitles, "It can't be!"

* Nanoha from ''Franchise/LyricalNanoha'' is famous for being a {{Determinator}} of epic proportions. So when she suffers a HeroicBSOD in ''[=StrikerS=]'' due to [[spoiler: Vivio getting kidnapped]], it holds that much more weight since it is the only time in the entire franchise that she acts that way.

* Played straight in the ninth ''Literature/TanteiTeamKZJikenNote'' novel which is animated as Episodes 9-12, when everybody else's being gravely concerned with Uesugi's well-being after (1)Dropping off Top 50 in math when [[GoodWithNumbers he always gets the first place]], (2) skips both CramSchool and TheTeam's proposed investigation, and (3) for an AcademicAthlete, the impossible feat of [[StaircaseTumble slipping off the staircase]]. Kuroki has to skip the case because of it, possible to handle Uesugi's problem. [[spoiler:Turns out the serious business is his vision has deteriorated to a point that he is already unable to read and a complete loss of vision is not impossible.]]

** Present Mic himself has had this twice. When he arrived at the [=USJ=] to see Aizawa bloodied and broken, he was furious and let the villains have his quirk full force. Later, he, Endeavor and Aizawa find tye doctor who made Oboro a Nomu. Mic is seething and beats the crap out of the guy.

* ''LightNovel/MyLadyJustWantsToRelax'': The usually mild-mannered king is absolutely furious about Schneider's behavior regarding Ronia. Seeing as how she would have made a very good queen and could now be taken by another kingdom, it's understandable.

-->"Chamber's response to Striker's final warning: ''[[PrecisionFStrike Go to hell, tin can]]!''"

--> '''Professor Kukui:''' ROWLET?! Rowlet, you're ''never'' awake! [[LampshadeHanging What's going on here?]]

** Sting spends the majority of the Grand Magic Games arc being the textbook ArrogantKungFuGuy, but the combo of [[BreakTheHaughty getting his (and Rogue's) ass beat by Natsu]] who wasn't going all-out, seemingly watching his best friend Lector get vaporized in front of his eyes [[BadBoss by his guild master]], and then learning Minerva is [[IHaveYourWife holding the actually-alive Lector hostage as insurance]] for him to win the Games by using ThePowerOfFriendship renders him eerily subdued and calculating for the final event. He spends his fights [[CombatPragmatist going for sneak attacks]] and holding a stony expression rather than his usual direct combat and boisterous attitude and then hides away from the cameras for most of the event letting the remaining fighters wear each other down while he conserves his strength. It's only near the end when it's all coming together than he lets some of the old cockiness back out.

** Also played straight: if Black☆Star is [[ChewingTheScenery not yelling]] and Death The Kid is not [[SuperOCD OCD'ing over symmetry]], prepare for an asskicking. Kid's an interesting example because the occasions he faces disorder and doesn't have a fit over it tend to be when he instead fixes on another inherent characteristic, that of him being a {{Shinigami}} (e.g Mosquito, minor point in his second fight with Black☆Star).

* In Chapter 75 of ''Manga/MyMonsterSecret'', an incident happened which causes the weather to get worse whenever someone acts out-of-character, and gets better when they act normal. When [[JerkAss Akane]] starts being nice, there was [[TheEndOfTheWorldAsWeKnowIt a huge storm with ''meteors'' falling down from the sky, as well as the Emperor of Fear descending to earth]]. Everything went back to normal, however, when [[ChristmasCake Akari]] shows up in a homely outfit. The chapter is also a BigLippedAlligatorMoment, as it was never explained what caused the phenomenon.

* ''LightNovel/{{Bakemonogatari}}'':

* In the ending of ''LightNovel/DemonKingDaimao'', the student council member [[VerbalTic who always says "guga"]], says something other than guga.
* In ''LightNovel/{{Durarara}}'', the rule is that if ''anyone'' goes out of character -- shit will happen.

* In ''LightNovel/FullMetalPanic'' Kaname begins acting completely differently after visiting [[spoiler:the ruined lab at Yamsk 11, including pulling a voluntary FaceHeelTurn]]. It turns out she's doing this because [[spoiler:it's ''not'' Kaname.]]

** In the [[Anime/FullmetalAlchemist 2003 anime]], you know [[ExtremeOmnivore Gluttony]] is upset over [[spoiler:the death of his [[PlatonicLifePartners platonic life partner, Lust]]]], when the thought of [[BigEater eating]] ''doesn't even cross his mind''.

** Normally, Eraser Head/Shota Aizawa keeps a dour TheEeyore attitude up at all times, while his old school buddy Present Mic/Hizashi Yamada is loud and bombastic. But when they're told that [[spoiler: their old friend Oboro Shirakumo might have been turned into a Nomu and become Kurogiri]], it's ''Aizawa'' who's furious and ''Mic'' telling him to calm down.

* ''Anime/MacrossDelta'':
** Freyja is a PluckyGirl par excellence who manages to move past her homeworld declaring war on ''the entire galaxy'', among tragedies with relative ease. Only two instances actually get ''her'' down; firstly, realising that [[spoiler: her singing is accidentally inflicting Var-like symptoms on [[LoveInterest Hayate]]]], and, in ''[[NonSerialMovie Absolute Live]]'', [[spoiler: realising her death is imminent and there is ''nothing she can do about it'']].

* ''LightNovel/AccomplishmentsOfTheDukesDaughter'': Sebastian is a grandfatherly figure to Iris and has a cool, calm demeanor. Whenever he drops this demeanor, everybody in and out of universe knows shit is going to hit the fan.

* ''LightNovel/ArifuretaFromCommonplaceToWorldsStrongest'': Suzu is normally a constantly happy GenkiGirl, so whenever she gets sad, it's a sign of just how dire things are.

* ''LightNovel/HaruhiSuzumiya'':

* In ''LightNovel/InvadersOfTheRokujyouma'', Kaera is a mild-mannered woman who dresses in the loose robes of an elder. Seeing her in her blue military uniform instantly alerts Nana to how serious the situation has become.

* ''LightNovel/RebuildWorld'': InvokedTrope by Akira’s VirtualSidekick Alpha. She’s a SmugSmiler who always keeps herself in Akira’s vision via AugmentedReality, and since that form is a mere digital avatar, she passively lets Akira know how much trouble he’s in with her body language, which often looks like DissonantSerenity while he’s fighting something he can handle. This makes it all the more impactful when she absolutely panics, or once, does a {{Facepalm}}.

* In ''LightNovel/ShakuganNoShana'', when Shana goes out of her way to avoid saying "[[{{Catchphrase}} Urusai! Urusai! Urusai!!!]]" for the most part, you know that some very serious shit is going down.

* Again like Gin, when Xelloss from ''LightNovel/{{Slayers}}'' opens his eyes, stops smiling, or [[EnigmaticMinion volunteers unambiguous information]], things have already gone completely downhill.

** Mai Koshiba is normally cheerful, unflappable and somewhat [[ManipulativeBastard manipulative]], although she can be serious when necessary. However, her demeanor changes when [[spoiler:Yoko Goeido, who left the salon on bad terms with everyone after breaking Nene Nishidera's heart]], pops by for a visit. Mai stops short in the middle of her usual greeting and is unusually subdued while the visitor is there. When [[spoiler:Goeido]] is on her way out, Mai subtly expresses that while [[spoiler:Goeido]] might be a paying customer, she doesn't want [[spoiler:Goeido]] around any longer than necessary.

* ''LightNovel/AccelWorld'':