History RedOniBlueOni / AnimeAndManga

** Jonouchi (Joey) and Seto Kaiba from ''Manga/YuGiOh'' follow this trope to the letter, right down to their trademark cards.
** Also, Yami Yugi (red) and Seto Kaiba when they duel together. Also present in their past incarnations, where Seto tends to calculate and plot behind the scenes.

* Inverted in a A racing genre manga, ''Manga/BakusouKyoudaiLetsAndGo'', the older sibling, Retsu, wearing red, is level-headed and careful, while Go, the HotBlooded and [[JerkWithAHeartOfGold bad behaving]] little sibling, wears blue. Their traits also show off in their customized mini 4wd racing machines.

* ''Anime/{{Daimos}}'': Richter is snarky and hot-tempered; Erika is serene and clear-minded. Richter is a ConqueringAlienPrince who wants to take over the Earth, while Erika works with LaResistance to stop him.

*** Subaru would tell a litaral story about it from his homeland to Ram, though it was about Red and Blue Orges than Red and Blue Onis.

* ''Anime/PokemonTheSeries'':
** Ash, the IdiotHero, as the perfect example of the Red Oni, while Gary, TheRival, definitely qualifies as the Blue Oni. Paul, Ash's new [[TheRival rival]], seems to have taken over the Blue Oni role, mixed with {{Jerkass}}. To a lesser degree, Zoey and Nando also qualify.
** From the first movie: the cute and cheerful Mew as the Red Oni to the badass and angsty Mewtwo as the Blue Oni.
** Zig-zagged with Roark and Byron. While both are {{Fiery Redhead}}s, Roark is usually more calm while Byron is one of the most HotBlooded characters of the anime, if not the most. However, Roark's offensive strategy has been portrayed as kind of reckless, while Byron's defensive strategy is shown to be more thoughtful.
** ''Manga/PokemonAdventures'' features the heroic trainer Red and his rival, Oak's nephew, Blue. In the Japanese original, however, this was not the case, as Red's rival was Green, while Blue was the female trainer that the English-language version called Green.

** The anime tends to use RedOniBlueOni in DPP.
*** Dawn and Zoey would count technically, but Zoey comes off as being the calmer one, so the colors are mixed up.

* Priss Asagiri and Sylia Stingray in ''Anime/BubblegumCrisis''.

* ''Manga/DemonSlayerKimetsuNoYaiba'':
** Faction leaders, [[BigBad Muzan Kibutsuji]] and [[spoiler: his distant relative]] [[BenevolentBoss Kagaya Ubuyashiki]], differ greatly in how they treat their subordinates. Kagaya is a kind, forgiving master, one who is willing to understand others and the world. The Hashira respect Kagaya greatly, viewing him as a type of [[TeamDad fatherly figure]], who suffers terrible woes unfairly. Muzan is the direct opposite, he's a [[BadBoss cruel, dominating figure]] one even the Upper Moons dread to cross or displease. Muzan punishes failure with instant death and mutilation, leaving his underlings terrified and desperate to earn his good favor. Kagaya asks only what his servants can do best, and [[MiseryBuildsCharacter accepts failure gracefully]].
* ''Manga/DragonQuestTheAdventureOfDai'' has the clashes between super-HotBlooded [[{{Tsundere}} Maam]] and borderline cowardly Pop. They're respectively dressed in red and pink and in green. Maam and TheStoic Hyunkel form an even bigger contrast, but they get along well while a large amount of screentime is devoted to [[SlapSlapKiss the conflict between Pop and his "badass goddess of luck"]]. Also, notice that Maam is a martial arts specialist and Pop a mage. Avan and Hadler are another interesting case, with Avan as the silly, warm-hearted, and spontaneous red oni (he's gotta have blue hair, but he's dressed in red]]) and Hadler as the stubborn and fiery but cold-hearted and stoic green-skinned warrior. Pop and Hadler become increasingly like their counterparts—the former through ThePowerOfFriendship and the latter through the magic of FoeRomanceSubtext.
* Kaoru and Rei from ''Manga/DearBrother''. Kaoru is sporty and sociable while Rei is reserved and angst-laden. Atypically, it's actually Kaoru who puts a leash on Rei, due to the latter's self-destructive habits.
* Miu and Ren from ''Manga/DearS'', Although Miu (Red) is a lot more orderly and educated than Ren she is prone to quick anger and has a large degree of pride in her nature. Ren (Blue) on the other hand is submissive, loyal and learns through more fluent communication and is by far more understanding between the two.
* Light and L from the ''Manga/DeathNote'' anime series are often shaded in red or blue to reflect this, although personality-wise, it doesn't ''quite'' apply, since aside from a few times that Light gets riled up after his cause is challenged ([[spoiler:and just before his death]]) both Light and L tend towards being brainy, cold blooded types. However, Light tends towards extremes of fantasy and pitches of emotion that L never begins to approach. This theme is also used (and generally played much straighter) with Misa and Light, Light and Near, Mello and Near, and even Misa and Takada.

** The ''Manga/{{Pokemon}}'' manga love this trope. [[Manga/PokemonDiamondAndPearlAdventure Hareta and Mitsumi]], [[Manga/PokemonGoldenBoys Gold and Black]], [[Manga/PhantomThiefPokemon7 Hiori and Lily]]...

* In ''Manga/{{Shiki}}'', the passionate doctor Toshio Ozaki pulls red oni duty while his lifelong friend, a melancholy monk named Seishin Muroi, plays the blue oni. Several of the important younger cast members exhibit this dynamic as well: among the girls there's excitable pink-haired Megumi (red) and her friend Kaori (blue) who has more neutral brown hair and a more reserved disposition. Kaori is also the blue oni to her orange-haired brother [[JumpedAtTheCall Akira's]] red oni. For the three main teenage boys, long-time antagonists Masao (red) and Natsuno (blue) have this dynamic, as lampshaded by their mutual friend Toru, who himself is the gleeful red oni to Natsuno's blue. Or, Masao is the blue oni while Tatsumi's red.

* In ''Manga/BlackButler'' Alois is the Red Oni to Ciel's Blue Oni. Alois is impulsive and more outgoing than Ciel while Ciel is calm and collected. They both have a red and blue color scheme respectfully as well. It's further driven home after [[spoiler:Alois' soul is trapped in a ring by Claude, it's red in contrast with Ciel's ring.]]
** A few more examples arise in the series; Grell and Sebastian (in an odd way), Lau and Ran-Mao, Alois and Claude, and to an extent Grell and Undertaker.

* ''Manga/{{Claymore}}'' has the main duo of Miria and Clare. From their personalities to their methods, these two are like night and day but when it's all said and done, they understand each other better than anyone else on their squad since both of their analytical skills and fighting power are nearly equal. They now fight in tandem with little to no communication needed between one another, managing perfectly synchronized attacks. As of late, some of Clare's recklessness has rubbed off on Miria, and likewise Miria's ability to lead and delegate team roles has rubbed off on to Clare.

** [[TheHero Natsu]] and [[TheLancer Gray]], who even have themed powers/auras.
** And also, hot-blooded lightning wizard Laxus versus calm, noble, blue-haired staff wizard Mystogan.
* Kirche and Tabitha from ''Literature/TheFamiliarOfZero''.

* ''Anime/HowlsMovingCastle'' has two sets, Sophie and Howl serve as Blue Oni's to Calcifer and Markl's Red Oni's.

* Played straight in ''Magika no Kenshi to Shoukan Maou'' with Amasaki Mio (red) and Hiakari Koyuki (blue). The two are love rivals (at least Amasaki thinks so) for the protagonist's affection, and they are also rivals for the top ranking in their class. Amasaki is a HotBlooded {{Tsundere}} and is very emotionally reactive, and her [[SummonMagic Diva]] is a phoenix; Hiakari is cool, calm, and self-conscious, and her Diva is a water/ice-type.

* They aren't quite colour-coded, but Tamaki and Kyouya of ''Manga/OuranHighSchoolHostClub'' seem to embody this trope rather well with cool-headed, intellectual {{Chessmaster}} Kyouya balancing up exuberant, people-focused ShelteredAristocrat Tamaki.

* ''Literature/{{Paprika}}'' and Dr. Chiba, [[spoiler:who are the same person]].

* ''Manga/PopTeamEpic'': Popuko has a nasty HairTriggerTemper, while Pipimi leans closer to TheStoic.
* ''Anime/PrettyCure''
** The titular duo of ''Anime/FutariWaPrettyCure'': Nagisa is the lacrosse-playing tomboy who wears the black and red costume, Honoka is the intellectual one in the white and blue dress. At one point, they even fight a pair of red and blue Oni just to drive the trope home.
** And, of course, their [[{{Expy}} Expies]] in ''[[Anime/FutariWaPrettyCureSplashStar Splash Star]]'' and ''[[Anime/SuitePrettyCure Suite]]'' fulfill the roles as well.
** In ''Anime/YesPrettyCure5'', this trope is played both straight and inverted. Cure Rouge and Cure Aqua play it straight, complete with a story showing how their opposite personalities clash. However, while Nuts usually wears red and Coco wears blue, especially in their human prince forms, Nuts is the quieter, more aloof one of the two, so they are the inversion of this trope (with the quieter one wearing red).
** In ''Anime/FreshPrettyCure'', Love is the red oni to Setsuna's blue. Interestingly, Setsuna is the who wears red while Love wears pink, but Setsuna also wears darker colors (especially black) in contrast to Love's bright clothes.
** ''Anime/HeartcatchPrettyCure'' also inverts this. The pink-wearing Tsubomi is a shy and introverted blue oni; her partner, the blue-wearing (and water elemental!) Erika, is an outgoing and energetic red oni.
** It's played straight again with ''Anime/SmilePrettyCure'' and its [[EverythingsBetterWithRainbows rainbow theme]] with Miyuki and Akane as Red and Nao and Reika as Blue. Yayoi (Yellow) falls in between.
** ''Anime/DokiDokiPrecure'': Mana is the red oni to Rikka's blue oni. Also, Alice and Makoto are blue onis to Mana's red. However, when Regina is there, she becomes the red oni to Mana's blue oni.

* Kyoko Sakura and Sayaka Miki in ''Anime/PuellaMagiMadokaMagica'', right down to the respective colors of their [[CurtainsMatchTheWindow hair, eyes]], and combat outfits. Madoka (outgoing, cheerful) and Homura (distant, aloof, collected) also fit, including their color identifiers (pink, gray).

** And pretty much everyone ends up playing the red oni when interacting with Kyubey.
* Ryoga and Mousse in ''Manga/RanmaOneHalf'', especially in their team-up episode to signify it.

* Joe and Ken of ''Anime/ScienceNinjaTeamGatchaman'', respectively.
** It varies with those two, actually. Usually, Ken is the steady, reliable one and Joe the impulsive, but later on, the roles reverse themselves, [[spoiler:namely during the final Red Impulse arc]].

* ''Manga/SeraphOfTheEnd'''s Yuuichirou and Mikaela are a prime example of this trope. Yuu is hotblooded, fiery, and full of [[BestServedCold determination]]. Mika, though having some [[Yandere/AnimeAndManga obsessive]] qualities, is level-headed, calm, and often a voice of reason to his companion.

* In ''Manga/{{Shiki}}'' the passionate doctor Toshio Ozaki pulls red oni duty while his lifelong friend, a melancholy monk named Seishin Muroi, plays the blue oni. Several of the important younger cast members exhibit this dynamic as well: among the girls there's excitable pink-haired Megumi (red) and her friend Kaori (blue) who has more neutral brown hair and a more reserved disposition. Kaori is also the blue oni to her orange-haired brother [[JumpedAtTheCall Akira's]] red oni. For the three main teenage boys, long-time antagonists Masao (red) and Natsuno (blue) have this dynamic, as lampshaded by their mutual friend Toru, who himself is the gleeful red oni to Natsuno's blue. Or, Masao is the blue oni while Tatsumi's red.
* Eiko and Chizuru from ''Manga/SquidGirl''.

** Later, Simon becomes the red to Rossiu's blue.

* ''Anime/{{Tamagotchi}}'':
** Downplayed with Mametchi and Memetchi, while both are passive tamagotchis, Mametchi is more level-headed, intelligent, and cries less, while Mametchi doesn’t cry much, Memetchi is ''very'' {{Prone To Tears}}.
** Out of the four main protagonists, Mametchi and Lovelitchi are the blue to Memetchi and Kuchipatchi's red, usually because Mametchi and Lovelitchi are calmer and Memetchi and Kuchipatchi are more emotional.

* ''Anime/YashahimePrincessHalfDemon'' shows the two half-demon twin sisters Setsuna and Towa. The wild, cranked Towa is the red oni, and the cool, reserved Setsuna is the blue oni. However, Moroha, the half-cousin of the two, is also there in most of the episodes. And she is so wild that compared to Towa she is the red oni and Towa the blue oni.

** Shota "[[PowerNullifier Eraser Head]]" Aizawa and Hizashi "[[MakeMeWannaShout Present Mic]]" Yamada, two of the teachers at UA High. One of them is Class 1-A's stoic SinkOrSwimMentor, the other is the fun-loving English teacher/[[LargeHamAnnouncer DJ]] with NoIndoorVoice. They've been friends since childhood.