I would like to share a few culture findings in the series:
*Pay particular attention to the "Yotsubox" in the corner of the tv room, where Yotsuba keeps junk treasures picked up in previous chapters, and which accumulates drawings of people she meets. Also, the wall above Koiwai's desk collects Yotsuba's drawings and photos.
*Yotsuba's stool for pancake-making is the little thing Koiwai made to practice for the bookshelf.
*Torako actually kept the dirty ball Yotsuba gave to her as a souvenir. Awww...
Yotsuba's hair is *always in those four little pigtails, even when sleeping, swimming, taking a bath, etc.
# No Cartoon Fish: More like No Cartoon Animals; all of the animals are photorealistic, though the fish, in particular, are disturbingly so.
*Counterexample: most dogs are cartoony, particularly those dogs Yotsuba barks back at.
*Smoking Is Cool: Why Yotsuba thinks Torako is awesome, even though her father told her that smoking is bad. Then again, Yotsuba claims that Koiwai used to smoke...
*Third Person Person: Yotsuba, childishly, in the original Japanese (mimicked in the Yen Press translations); she combines this with an innocent imitation of her father's masculine idiom, which is nothing short of hysterical — an effect that, alas, is Lost In Translation.
*Where The Hell Is Springfield: The suburban setting of the series is not clearly defined, being something of a stand-in for suburbs everywhere in Japan. For what it's worth, the locations are drawn from photographic references taken around the author's home in Hyogo Prefecture, and the presence of a Danjiri Festival in autumn places it pretty concretely in the Kansai region. However, characters generally speak Standard Japanese, though that means little in fictional works not set in a concrete location, and Yotsuba's occasional Kansai vocabulary can be excused via too much TV and Rule Of Funny. Let's just say the question remains open.
*Also, no one has any idea where Yotsuba was born and/or used to live. All she'll say is that it was "an island to the left."