[[CodeGeass http://tvtropes.org/pmwiki/pub/images/code44qx.jpg]]
[[caption-width:320:[-Ah ha! Let me be [[MemeticMutation your Spellcaster!]]-] ]]

If your show is aimed at a younger audience, this young woman (usually in her mid to late teens, sometimes in her early 20's) will be older than the {{Shorttank}} and be the girl everyone thinks is hot (if they're nice) or a slut (if they're not). The Shorttank girls often admire them, even when they playfully flirt with the much younger male lead and steal everyone's attention. Also, the YamatoNadeshiko or ShrinkingViolet girls will admire and at the same time envy how more open their Big Sister figure is with her thoughts and feelings.

This young lady may or may not catch a {{shonen}} series lead's eye; if he hasn't entered puberty yet, she's more likely to be paired up with either TheBigGuy, the TeamDad or the BigBrotherMentor. Or ''maybe'', if she's persistent enough, she'll end up in an OddCouple with an AloofBigBrother or a single HotShoujoDad. She may also evolve into a TeamMom thanks to CharacterDevelopment.

Expect a somewhat jaded, cynical character who prefers to work the system in their favor rather than admit to others she's become cynical. If old enough to drink, she may also be a BottleFairy, or even TheLadette; if not, she'll often be a LethalChef and/or BigEater. If older than the standard, she might be a ChristmasCake as well.

Compare OneeSama, also a sister figure but usually more ladylike, quiet and graceful.

-----
!!Examples:

[[foldercontrol]]

[[folder: Anime and Manga ]]

* Pictured above: Milly Ashford, the StudentCouncilPresident from ''CodeGeass'', is actually referred to on the show's official website as a "reliable older sister" to her friends (when she isn't tormenting them with her playful antics and "magic spells"). She's one of the more popular side characters due to this, as well as her...um...[[MontyPythonAndTheHolyGrail huge tracts of land]] and [[FetishFuelStationAttendant eagerness to grope the female Student Council members]].
* Misato Katsuragi in ''{{Neon Genesis Evangelion}}''. Or at least, she attempts to be one.
* Mai Kujaku/Valentine in ''{{Yu-Gi-Oh}}''.
* Urd of ''{{Ah My Goddess}}'', to both younger sister Skuld and Keiichi on occasion, though with mixed success.
* Nice Holystone and eventually [[spoiler: Ennis]] from ''{{Baccano}}''
* Shigure Asa of {{Shuffle}}, who is also a GenkiGirl {{Bokukko}} to boot. [[spoiler: And she's the one who gets the guy]]
* Seiji's big sister Rin in ''MidoriNoHibi'' is a mild exaggeration and subversion. Seiji's already pretty damned cool himself, but his sister is over the top -- although she dresses like an OfficeLady, she leads a biker gang, and generally takes all the usual Cool Big Sis behaviors to an obnoxious extreme. The only human being - he describes her as a demon - he fears. She does, however, sincerely care for her little brother and wants him to be happy. Which explains why she put him through TrainingFromHell as a child. of course, she ''did'' seem to enjoy it...
* Haruka Urashima in ''LoveHina'' probably counts.
* Haruka Minami from ''{{Minami-ke}}'' ''definitely'' does.
* Override in ''[[{{Transformers}} Transformers Cybertron]]'' fits the type even if she ''is'' a [[HumongousMecha Giant Robot]]. She even refers to one of the humans as "little sis".
* Nobue in ''IchigoMashimaro''.
* Kasumi (Misty) in ''{{Pokemon}}'' has not one, not two, but ''three'' Cool Big Sisters, actual sisters at that. She doesn't exactly idolize them, though, getting along only with the eldest of the trio.
** A more straight example is LadyOfWar Soledad (Saori) from ''Advanced Generation'', who acts like a cool big sis to May and Drew.
* Nikora in ''MermaidMelodyPichiPichiPitch''.
* Kaya, [[spoiler:more specifically, her alter ego Nagato-sensei,]] in ''Mugen Densetsu Takamagahara: DreamSaga''.
* Gascogne fills the role in ''{{Vandread}}''.
* Raquel Casull in ''ScrappedPrincess''.
* Michelle Cheung, the eldest of the three Paper Sisters from ''[[ReadOrDie Read or Dream/R.O.D The TV]]''.
* Hevn in ''GetBackers''.
* Kuwabara Shizuru in ''YuYuHakusho'', actually Kuwabara Kazuma's older sister, who seems to consider it her job to keep the younger (acting?) girls safe and upbeat. Urameshi Atsuko kinda shifts between this and HotShounenMom in the manga... she had Yuusuke when she was about ''fourteen'' (Yuusuke's same age), after all.
* Satella from ''ChronoCrusade'' could possibly fit this trope, except that nobody seems to look up to her at all (and Rosette, in fact, is rather put off by her in general, ''especially'' when she flirts with Chrono).
** [[TheChick Azmaria]], maybe? In the anime, at least. There's a lovely scene where Satella combs her hair, [[spoiler:right before everything goes [[DownerEnding straight to hell]].]]
* Azusa Miura from ''The Idolm@ster''.
* Triela fills this role in ''GunslingerGirl'', despite not being related to any of the other protagonists.
* Technically she's the ''cousin'' of [[TroubledButCute Ryoma Echizen]], but otherwise Nanako Meino fits the trope to a T in ''ThePrinceOfTennis''. And there's also Fuji's [[HelloNurse EXTREMELY hot sister]] Yumiko as well...
* Sakaki from ''AzumangaDaioh'' is pretty much this, being quite protective of [[TheCutie Chiyo]][[CheerfulChild -chan]] and earning Chiyo's admiration in return. And then there's all her in-show {{Fangirl}}s...
* Yoko Littner from ''TengenToppaGurrenLagann'' becomes this after outgrowing her {{Tsundere}} stage early in the show, although she had hints of it from the beginning.
* ''BitterVirgin'' has Izumi Suwa, elder sister of Daisuke, who is considered a CoolBigSis by Daisuke's childhood friend Yuzu Yamamoto. She also becomes such to female lead Hinako when she encourages her to fight for Daisuke's affections and becomes [[spoiler: the only person who Hinako has knowingly divulged her secrets to]]. She also earns some points in this troper's opinion for casually dismissing the flak she catches for returning to her conservative home town ''very'' pregnant with no father in sight.
* Mai Tokiha from ''{{Mai-HiME}}'' who, atypically for this trope, ''is'' a {{shonen}} series lead. She jokes about Shiho's BigBrotherComplex toward Yuuichi when they all first meet, stating that she (Mai, not Shiho) and Takumi are blood-related.
* Yuki in ''HourouMusuko'' is a Cool Big Sis, with [[{{Transsexual}} a slightly modified definition of "Sis".]]
* Ginga Nakajima, Subaru's older sister in ''MagicalGirlLyricalNanoha''. Nanoha often seems to fill the role as well to the Forwards.
* Lin ([[SpellMyNameWithAnS Rin]]) in ''Spirited Away'', who is not actually Chihiro's sister but acts like one.
* Christina Sierra from {{Gundam 00}} isn't the sister of either Feldt or the Gundam pilots, but treats them as if they were her siblings.
** She possibly caught that from Catherine "Cathy" Bloom, the cool big sister from ''GundamWing''. [[spoiler: Who may nor may not be the long lost sister of the Gundam Heavyarms's pilot, Trowa Barton]]
** And let's not forget Toniya, the DarkSkinnedBlond from AfterWarGundamX, who plays this role towards Tiffa and Garrod ([[ShipperOnDeck and even ships them together]])
* Claudia [=LaSalle=] (or Claudia Grant, if we go by ''Robotech'' names) from {{Macross}}
* Rangiku Matsumoto from ''{{Bleach}}''. She really takes on the CoolBigSis role when she lives with Orihime.
** And to a lesser extent, Yoruichi Shihoin. Teases the hell out of Ichigo, after abandoning cat form and [[{{Nosebleed}} appearing nude]] in front of him, revealing his prudishness. Also was the mentor and idol of a teenage Soifon, who ended up developing quite the BodyguardCrush on her.
* Tsubaki Doumyouji and Shizuka Todou from ''HanaYoriDango''.
* Yukari from KimagureOrangeRoad. Madoka also was the CoolBigSis for Yuusaku, Hikaru and the Kasuga twins.
* Sylvie "Songbird" Arte is this to the lead girl from ''AshitaNoNadja''.
** Also, [[TheOjou Julietta]]. [[spoiler: When Nadja is caught in a LoveTriangle with the twins Keith and Francis, Julietta tells her "Choose the guy ''you'' truly want!". It works, and Nadja picks Francis.]]
** Curiously, ''Nadja herself'' used to be the CoolBigSis of her OrphanageOfLove.
* Katie Taylor and Pamela (also a HotShounenMom) from ''KaleidoStar''. Sarah Dupont is ''both'' this and the local TeamMom.
* Natsumi Hayama from ''KodomoNoOmocha'', after her CharacterDevelopment.
* In ''OvermanKingGainer'' after she switches sides, Adette eventually becomes this role, well after she stops sleeping. The Siberian Railroad even still calls her Big Sis while she's attacking them.
* Tamaki Kousaka from ''{{To Heart 2}}'' is the CoolBigSis to Takaaki.
* Played for laughs with Li Syaoran's ''four'' older sisters in the first CardCaptorSakura movie. They were all very sweet and well-intentioned... and complete {{Kawaiiko}}s.
* Both [[HelloNurse Dr. Yamaguchi]] and [[HotScoop Mari Iizuka]] from ''HajimeNoIppo''.
* Hungary from AxisPowersHetalia, before she "graduates" into TeamMom and marries Austria.
** In Finland's notes, Belgium is hinted to be a CoolBigSis too, but she has only had cameos so far.
* Melissa Mao from ''FullMetalPanic''. She mentions the trope almost by name in ''The Second Raid'' when she confronts Sousuke about [[HeroicBSOD spacing out in the middle of a mission]]. Not to mention that Kurz calls her "Sis."
* Rin Ataka from ''Gasaraki'' is arguably one of these too, she even goes so far as to sneak off of a military base despite being detained in order to check if Yushiro is ok.
* Fasalina in ''GunXSword'' is amongst the antagonist's group, however she seems fond of newcomer Michael and if he's not being guided by The Claw, he goes to her and she teaches him. It doesn't excuse her position as a villain though, making her a rare villainous CoolBigSis.
* ''MahouSenseiNegima'' has Negi's cousin Nekane filling his role whenever she's around. Kaede, Konoka, Akira, and Chizuru all fit the bill as well.
* Asagi in ''[[{{Yotsuba}} Yotsuba&!]]''.
* Tae Sekihara in ''RurouniKenshin'', who counsels her friend Kaoru and takes Tsubame under her wing.
* Kirino Chiba, ''BambooBlade'''s KendoTeamCaptain, is more ditzy than flirty, but is clearly remarked to be the CoolBigSis for the kendo team, which helps to keep them united. This may also make her something of a TeamMom.
* Anehara Misa in ''{{Yoku Wakaru Gendai Mahou}}.''
* So far, Eva from ''{{Karneval}}'' is one to some extent, being reliable during a crisis, [[LesYay especially when Tsukumo-chan is concerned]], although the guys are pretty scared of her.
* Chikaru of ''StrawberryPanic''.

[[/folder]]

[[folder: Film ]]

* ''BonCopBadCop'' had a Cool ''Younger'' Sis for the strait-laced, by-the-book Ontario cop. Naturally, the chain-smoking, rulebreaking, yet oddly charismatic Quebec cop was interested.

[[/folder]]

[[folder: Video Games ]]

* A particularly odd example of this trope can be found in the game ''Persona 2: Innocent Sin'', released only in Japan. It's odd because the four younger kids she played with [[spoiler:locked her in a shrine so she wouldn't have to move away. Of course, the shrine catches on fire and they [[NeverFoundTheBody think they've killed her]].]] And that's just the tip of the iceberg.
* Jennifer, sidekick of '''Captain Gordon, Defender of Earth!''', in ''{{Disgaea}}''.
* Excellen Browning of ''SuperRobotWars'' is perpetually cheerful, friends with everybody (especially Lamia Loveless and Einst Alfimi) and an unabashed MsFanservice. In fact, Excellen plays on this trope by having Lamia address her as "Ex-oneesama" when they first meet.
** Likewise, the TallDarkAndBishoujo Ouka Nagisa of The School Children is the eldest and addressed by Arado Balanga, Seolla Schweizer and Latooni Subota as their "sister".
* Nanami from ''SuikodenII''.
* Bleu/Deis from the ''BreathOfFire'' series is somewhat of a CoolBigSis to the party - most notably in 3 and 4. She guides and gives hints to Ryu and his party, and is definitely the most... erm... endowed woman in the party. Interestingly enough, Ryu ''does'' express romantic interest in her (pretty much the most you'll ever see him express towards anyone, considering he's a SilentProtagonist) in 3, sort of culminating in a [[PrecociousCrush little kiddy crush]]. Probably has to do with how he saw her [[BigBouncyBreasts full front]], [[NakedOnArrival completely naked and up close]].
* Teased with Grandia III. Everything you've seen indicates Miranda is a CoolBigSis, until it's revealed she's a HotShounenMom instead. Her personality, however, fits this trope.
* Letty Whiterock of ''[[{{Touhou}} Perfect Cherry Blossom]]'' is one of these for the [[TheDitz ditzy]] [[AnIcePerson ice fairy]] Cirno.
* Tamara from ''CustomRobo Arena''.
* Ellone from ''FinalFantasyVIII'' served this purpose for the rest of the orphans in the backstory.
* Inferno from ''[[SaniTarium Sanitarium]]''

[[/folder]]

[[folder: Webcomics ]]

* Dora of ''QuestionableContent'' had this sort of relationship with Faye and Marten, until she hooked up with the latter.
* During the "Phoenix Rising" arc of ''SluggyFreelance'', Oasis takes on this role to Katie. Since Oasis is a semi-psychotic assassin/vigilante with an AllCrimesAreEqual attitude, this ''really'' freaks out Katie's mom.
* Murf's sister Kelly in ''KhaosKomix''.
* ''{{Misfile}}'': Once she lightens up after [[spoiler:Rumisiel exorcises her dead older sister's vengeful spirit]], "Kamikaze" Kate becomes one of these, ''insisting'' on making Ash her "little sister".

[[/folder]]

[[folder: Web Original ]]

* Sarah in ''[[ErikasNewPerfume Erika's New Perfume]]'', after [[PlotRelevantAgeUp certain events]].

[[/folder]]

[[folder: Western Animation ]]

* Jerrica Benton of ''{{Jem}}'' plays this role for the kids at her orphanage.
* ''KimPossible'', actually the eponymous main character of her show.
** Also, when her [[ArchEnemy nemesis]] Shego was turned good and became her friend, Kim described her "like a big sister".
* Flash from ''JusticeLeagueUnlimited'' considers Hawkgirl as one of these. In his words:
-->"She loves me. She's like the big sister I never had. Only, y'know, short."
* Irma and Cornelia in {{WITCH}}.
* The XMenEvolution rendition of Jean Grey, also a Type B {{Tsundere}}.
** Tabitha Smith, aka Boom-Boom, ''really'' fits the bill after her CharacterDevelopment.
* Daisy Dingo from BlinkyBill
* Jazz Fenton in DannyPhantom.
* Jen on [[{{Sixteen}} 6teen]] has a mean older sister everyone loves that she's jealous of.
* Yumi Ishiyama from ''CodeLyoko'', if she counts...

----
<<|AlwaysFemale|>>
<<|AnimeCharacterTypes|>>
<<|SiblingTropes|>>