http://static.tvtropes.org/pmwiki/pub/images/Chokotto_Sister.jpg
Haruma Kawagoe has had the lifelong wish of being an older brother. However, after a miscarriage and an [[http://en.wikipedia.org/wiki/Hysterectomy operation]], his mother could not give him a little sister. Nevertheless, [[{{Determinator}} he never gave up on his wish.]]

One Christmas night, during his college days, Haruma has a huge present delivered through his window by a woman on an airborne motorcycle claiming to be SantaClaus. The present contains the little sister he always wanted, and Santa justifies the time it took to fulfil his wish by saying that ''making a little sister takes a lot more time than just making an android''.

This [[{{Moe}} cute]] manga and anime follows Haruma's life as he attempts to adjust to suddenly having a little sister out of the blue, especially a little sister [[HilarityEnsues who has an instruction manual with material inappropriate for her age, and follows it religiously.]]

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!!Tropes this show has examples of:

* AccidentalPervert: Inverted in episode 4. Makoto pushes Chitose into Haruma's apartment. Poor Haruma, he was only wearing a towel.
* AllLoveIsUnrequited: Taken to almost absurd levels - literally ''every single character'' except Choco is in love with someone totally oblivious.
* CaptainErsatz: "[[Creator/QuentinTarantino Tirantano]]", "Cancent Villo", "[[Film/BuffaloSixtySix Buffalo 99]]", to name a few.
* ChildhoodMarriagePromise: In the manga, [[spoiler:Haruma made one to his cousin Konatsu]].
* ChristmasEpisode
* CloudCuckoolander: Chitose has a rather vivid imagination
* {{Cosplay}}: Not so much in the series proper, but the below-mentioned {{dancing theme}} is obviously aimed at cosplayers--[[http://www.youtube.com/watch?v=8qFZNkFDAgQ and not without success]].
* CrouchingMoronHiddenBadass: Yasuoka, the lethargic unemployed neighbor at the protagonists' apartment building, is actually a former detective and aikido expert.
* DancingTheme: [[EarWorm Neko Nyan Dance]], anyone?
* DefrostingIceQueen: Yurika.
* EroticEating: Done by Choco with a chocolate-frosted banana
* EyesAlwaysShut:
** Tamami, With one, blink and you'll miss it exception in episode 6 [[http://i426.photobucket.com/albums/pp349/prisoner_24601/vlcsnap-2012-12-24-00h16m52s52_zps01b79a03.png As pictured in this screencap]], her one eye partially opens for a brief moment.
** Yasuoka as well, though less as noticable
* ExtremeDoormat: Chitose.
* {{Fanservice}}: Quite a bit of it
* FluffyTamer: Choco, with Kuro the panther.
* FuroScene
* GirlInABox: specifically, a little sister delivered in a present. Oh, and it's a bag, not a box
** Done twice in the valentine's day episode with a box, the first time was {{all just a dream}}, the second, well, didn't end so well for poor Choco [[spoiler: Haruma tapes the box shut and shoves it into a closet, much to Choco's dismay]].
* TheGlomp: Choco loves doing this to Yurika.
* HadakaApron: worn by Choco at one point because her manual says that older brothers love this sort of thing.
* HardDrinkingPartyGirl: Makoto, one of the tenants where Haruma is staying, who also loves to [[SkinshipGrope tease]] their landlord.
* HotSpringsEpisode
* [[spoiler:{{I See Dead People}}]]:[[spoiler:Choco meets Yasuoka's deceased daughter and wife at the amusement park]].
** [[spoiler:In the manga's finale, Choco has a similar encounter with Kuro the panther and a woman revealed to be Yurika's mother.]]
* {{Kawaiiko}}
* {{Landlady}}: Chitose
* LovableSexManiac: Makoto, although she [[BlackComedyRape tends to go a bit far]] in her teasings at times.
* {{Meganekko}}: Chitose
* {{Meido}}
* NoSocialSkills: Choco has no experiences in life at all, and relies entirely on her inappropriate manual.
* {{Ojou}}: Yurika. Her home is ''huge''.
* [[OrdinaryHighSchoolStudent Ordinary College Student]]
* PantyShot: To the point of ruining a very emotional scene.
* PromotionToParent: Choco's arrival forces Haruma into this. Luckily he gets a lot of help (?) from his neighbors.
* PutOnABus: [[spoiler:Ayano]].
* [[spoiler:{{RetGone}}]]:[[spoiler:Choco, at the end of episode 22 and through most of episode 23, after Haruma insists to his cousin that he has no little sister.]]
** [[spoiler: though nobody remembers Choco directly, her presence still existed in their unconscious memories, as well as other indirect evidence of her existence remained, which eventually clued Haruma to finally remember Choco]]
* SantaClaus: Well, ''a'' Santa, if not the actual old cheerful man.
* SdrawkcabName: [[spoiler:Ashirai Makoto and Otokami Alisa]].
* ShouldntWeBeInSchoolRightNow: One should worry for Choco's future, seeing as she never gets any education.
* ShoutOut: One of the last chapters features a picture of ''{{Yotsuba}}'''s main character Yotsuba on a milk carton.
* ThemeTuneCameo: The ending theme, Neko Nyan Dance, is the {{Dancing Theme}} of an in-universe children's TV show. One episode centers around the apartment residents making a video of themselves performing the dance.
* {{Tsundere}}: Yurika, voiced by none other than {{Rie Kugimiya}}.
* {{Tsurime Eyes}}: Hideko, Yurika's maid, sports them.
** Not to mention Yurika and Makoto. [[spoiler: Ayano's fiance also sports them]]
* UndeadTaxExemption: Choco's appearance somehow doesn't cause any problems.
* WhyDoYouKeepChangingJobs: Tamami.
* ZettaiRyouiki: Yurika.
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