Haruma Kawagoe has had the lifelong wish of being an older brother. However, after a miscarriage and an operation, his mother could not give him a little sister. Nevertheless, 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 Santa Claus. The present contains the little sister he always wanted, and Santa justifies the time it took to fulfill his wish by saying that making a little sister takes a lot more time than just making an android. The story follows Haruma's life as he attempts to adjust to suddenly having a little sister out of the blue, especially a little sister who has an instruction manual with material inappropriate for her age, and follows it religiously.
Chocotto Sister is a seinen manga written by Go Zappa and illustrated by Sakura Takeuchi, which was serialized in Young Animal from 2003 to 2007. It was later adapted to a 24-episode anime series in 2006.
Tropes this show has examples of:
- Accidental Pervert: Inverted in episode 4. Makoto pushes Chitose into Haruma's apartment. Poor Haruma, he was only wearing a towel.
- All Love Is Unrequited: Taken to almost absurd levels - literally every single character except Choco is in love with someone totally oblivious.
- Captain Ersatz: "Tirantano", "Cancent Villo", "Buffalo 99", to name a few.
- Childhood Marriage Promise: In the manga, Haruma made one to his cousin Konatsu.
- Cloud Cuckoolander: Chitose has a rather vivid imagination
- Crouching Moron, Hidden Badass: Yasuoka, the lethargic unemployed neighbor at the protagonists' apartment building, is actually a former detective and aikido expert.
- Diegetic Soundtrack Usage: 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.
- Erotic Eating: Done by Choco with a chocolate-frosted banana
- Eyes Always Shut: Tamami's eyes are always closed, with one exception: in episode 6◊, she briefly opens one eye.
- The Glomp: Choco loves doing this to Yurika.
- I See Dead People:
- Choco meets Yasuoka's deceased daughter and wife at the amusement park.
- In the manga's finale, Choco has a similar encounter with Kuro the panther and a woman revealed to be Yurika's mother.
- Manic Pixie Dream Girl: Choco proves that you needn't be a potential love interest to fulfill this role; Choco shows all the cheerfulness, innocence, and absolute devotion that defines a MPDG. Fortunately, she does not keep the original meaning of a zero-development plot device, but actually develops a great character of her own from this start.
- Naked Apron: Worn by Choco at one point because her manual says that older brothers love this sort of thing.
- No Social Skills: Choco has no experiences in life at all, and relies entirely on her inappropriate manual.
- Promotion to Parent: Choco's arrival forces Haruma into this. Luckily he gets a lot of help (?) from his neighbors.
- Ret-Gone: 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. 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.
- Santa Claus: Well, a Santa, if not the actual old cheerful man.
- Sdrawkcab Name: Ashirai Makoto and Otokami Alisa.
- Shouldn't We Be In School Right Now?: One should worry for Choco's future, seeing as she never gets any education.
- Shout-Out: One of the last chapters features a picture of Yotsuba&!'s main character Yotsuba on a milk carton.
- Undead Tax Exemption: Choco's appearance somehow doesn't cause any problems.