* AngstWhatAngst: Yotsuba was either orphaned or abandoned overseas, then taken in and raised by Dad. At least partly justified, since Yotsuba seems to have been too young to remember her real parents, and anyway, what matters to this story is that she's happy and healthy ''now''.
* EnsembleDarkhorse: Cardbo/Danbo, the cardboard robot, who got an action figure despite having only appeared in two chapters that are far apart, and he has even ascended to the noble position of Official Mascot of Amazon.co.jp. Just don't tell Yotsuba it's Miura in a costume made for a school assignment. He even comes with his own ''customizable'' plastic model! [[http://www.collectiondx.com/news_item/2912/danboard_kit_kotobukiya BEHOLD!]]
* FanPreferredCouple:
** There is little to no romance in the series itself, but Koiwa X Fuuka is easily the fan favorite. It helps that most of the {{ship tease}} that exists in the manga at all are between them.
** For [[YuriFan some fans]], Asagi x Torako is a popular ship even though the two, as far as what is shown is concerned, are just close friends that hang out a lot.
* HollywoodHomely: Fuuka is often unfavorably compared to Asagi, whose beauty is constantly praised and has gotten the attention of Jumbo and Yanda. Yotsuba goes as far as to call Asagi and Fuuka the "pretty sister" and "not-pretty sister" respectively before she remembers their names properly in the 2nd chapter. Though there are times when we are reminded that yes, Fuuka is considered very attractive. The first time is when Jumbo ''does'' actually call her a Bishoujo[[note]]"pretty girl"[[/note]] when he meets her, he's just also quick to demote her to "just a shoujo" after he meets Asagi; and then at the pool Koiwai and Jumbo are stunned by the sight of Fuuka in a two piece swim-suit, and when she teasingly asks Jumbo if they are stunned at her sexiness, Jumbo seriously states "Yes" before quickly back tracking and playing it off as a joke.
* HollywoodPudgy: Fuuka is frequently stated to have fat legs, and is even teased about this by Asagi and their mother. Look at a picture of Fuuka alongside any other teen girl character in the series, and see if there's ''any'' major difference in their body types. Then again, Asagi and mom are jerkasses at times, so they could just be messing with her. Asagi even tells Tora off once for saying she has fat legs, saying Tora is just too skinny.
* LesYay: Asagi is never seen socializing with anybody outside of family and her neighbors--except for Torako. Asagi and Torako also love to go on long outings together, and [[YuriFan some people]] feel those show all the telltale signs of actual dates. It helps that the outings we know of, do indeed seem like date spots; an Okinawan beach, a Hot Air Balloon race, and a Firework Display. Its also shown that these outings are always, or at least planned, for just the two of them. It doesn't help that when Jumbo demands to know who "[[GenderBlenderName Tora]]" is, after Yotsuba draws a picture of Asagi and her, in which it is impossible to tell Torako's true sex. Yotsuba describes Tora in a way that sounds like Tora is Asagi's boyfriend[[note]] In the original Japanese Yotsuba doesn't use any gender specific pronouns[[/note]], much to Jumbo's [[HeroicBSOD dismay]]. It becomes something of a running gag later on.
* MemeticMutation:
** Yotsuba is used as a mascot by some ImageBoards, most prominently 4chan, which uses a clover as its logo and runs on a modification of Futaba called Yotsuba.
** It is also exemplified ''within'' the series by the teddy bear Duralumin, who shares a name with a metal alloy but is really Yotsuba's [[{{Malaproper}} mispronunciation]] of ''Ena's'' stuffed bear Julietta.
* {{Moe}}: 5-year-old GenkiGirl Yotsuba is '''incredibly''' adorable and is is fawned over even in-story by fellow characters who mostly have a soft spot for her.
* NoYay: Quite a few people prefer the ship tease to stay subtle and go nowhere.
* PeripheryDemographic: Yotsuba herself is the loveable mascot of 4Chan, and Anonymous is [[EvenEvilHasStandards fiercely protective of her]].
* SacredCow: Don't even mention anything that involves RuleThirtyFour images of Yotsuba of any sort to Anonymous. Thankfully made easier by the fact that there isn't all that much to begin with.
* {{Shipping}}:
** A popular ship is Koiwai x Fuuka, prompted by their multiple interactions (including classmates asking Fuuka if Koiwai is her "husband") and hinted at in Azuma's proto-comic for ''Yotsuba&!'', "Try! Try! Try!". The multiple blush-inducing situations that Fuuka experiences around Koiwai (including the paper-cup telephone [[NotWhatItLooksLike conversation]] and a comment in Chapter 67 about how her [[BigOlEyebrows eyebrows are cute as they are]]) do not help this. That Azuma in a side comment was "scared" by Fuuka's classmates finding Koiwai attractive hasn't deterred shippers.
** In chapter 61, Koiwai gives Yotsuba a "helicopter ride" (swinging her around by the arms so her feet leave the ground). Then Asagi lines up to try it, and seeing them circling each other hand in hand, Torako comments that "they seem to get along together really well". A few chapters later, Koiwai teases Jumbo with a picture of it.
** Close friends Asagi x Torako shipping, as seen in the LesYay entry.
** [[HoYay Koiwai and Jumbo's]] closeness with each other have garnered a few fans for the ship. Koiwai is never seen with other friends (besides Yanda), Yotsuba is convinced Jumbo is his only friend, and some panels of the two of them with Yotsuba make them look a lot like [[HasTwoMommies two fathers]] with their daughter.
** Miura tends to get shipped with [[LesYay Ena]] as they hang out with each other a lot and no one else their age. She's also more frequently and more ''[[{{Squick}} disturbingly]]'' shipped with [[HugeGuyTinyGirl Jumbo]] due to their SitcomArchNemesis friendship.
** There has been some Yanda x teenaged Yotsuba, since if she was older their relationship would have all the makings of a SlapSlapKiss romance.
* ShipToShipCombat: Hardly bloodthirsty but it pops up on occasion. For example since the Balloon arc, some have started to prefer Koiwai with Asagi over Fuuka, and then ship Fuuka with Jumbo. Of course there are those who still prefer [[ShipMates Asagi with Torako and Fuuka with Koiwai]].
* SweetDreamsFuel: No one can resist Yotsuba's cheerful attitude toward her life, NO ONE.
* UnacceptableTargets: Almost the TropeNamer, due to her being a 5-year-old that is adorable and innocent in nature. Even in [[EvenEvilHasStandards the darkest depths]] [[ImageBoards of the Internet]], Yotsuba Is Off Limits.
* WatchItForTheMeme: Or in this case, Read It For [[ImageBoards 404 Girl]].
* ViewerGenderConfusion:
** Miura has BoyishShortHair and wears boyish clothes, so many readers mistake her for a boy in her first appearance. Even Jumbo has to ask if she's a boy or girl not long after first meeting her.
** Torako also has short hair and doesn't dress femininely so she can confuse readers too. The only physical hints of her gender are her chest and the slight eyelashes found on most of the female characters.
** Koiwai has shaggy shoulder-length hair and his facial features are on the softer side, so readers often mistake him to be female until they see Yotsuba calling him Daddy in the first chapter.