Nope, Kiyohiko Azuma didn't draw that. I just googled it and it was drawn by the author of Pretty Neighbor, and also this doujin about Osaka. This dude really can draw with a style similar to Azuma's.
In fact, that page you posted comes from Pretty Neighbor number 7, even though it's not porn.
I don't know if the translation is real, but may be since a lot of people seem to want to know where Yotsuba came from in the canon of the manga, which is a question I don't think will ever be answered. In fact, I don't think we need it answered, and Azuma himself may not know.
I found a theory on Tumblr:
> There's theories that she's from North Korea because she's afraid of targets and whenever she hears something loud she goes "we're under attack"I think that makes sense, but also I think coming up with theories is missing the point. Yotsuba is a story about very simple things, and introducing a canonical origin would complicate everything.
That being said, if I had to have a theory I would say she's Irish.
That's my old head-canon.
-Yotsuba's head is a four-leaf clover
-Green is a dominant color in the covers
-There are terrorist attacks in Ireland even today, would explain why she thinks fireworks are "the enemy"
-She was born in an island
-Koiwai knows English, and although he may know other languages, we know for sure he speaks English and we have no confirmation that he knows Korean
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