Okay, but what about ASEXUAL YUKARI TANIZAKI?

Some characters in Azumanga Daioh are decidedly sexual, judging from their reactions to the topic: Tomo, Nyamo, Kaorin, Kimura. (Kaorin expresses physical attraction to Sakaki a few times, something I interpret as sexual arousal). Osaka is neither oblivious nor uninterested, but she doesn’t make a big deal out of it either (I headcanon her as graysexual). Kagura and Sakaki seem flustered rather than intrigued, while Yomi comes across as mostly indifferent. And Chiyo-chan, being a child, is completely innocent. It’s possible that some of the aforementioned characters are gray/demi or ace as well.

Yukari, though? There is no indication of her either having a sex life or wanting one. This is her reaction when Tomo asks for dirty stories:

And after Nyamo gave the girls the talk (notice how Yukari doesn’t tease her or get excited over last night’s events):

It seems that Yukari isn’t completely put off by the thought of romance, though, as seen in the strips shown below. But I still have reason to believe she’s on the aro spectrum (I’ll get to that).

It is, of course, possible that Yukari wants to get married mainly for financial stability and/or living up to society’s expectations. In fact, Nyamo is usually depicted as quite lovesick compared to Yukari, and way more experienced. Yukari seems not to have a problem with that – it doesn’t pique her jealousy or competitive spirit.

I like the headcanon of Yukari being asexual and grayromantic, which is supported by the source material, albeit not explicitly stated. It’s rare to find a character so extroverted, eccentric and fun-loving who has no known interest in sex. Tomo parallels Yukari in many ways, and she’s by far the most openly sexual (female) character in the story, but this is a point where they differ. It’s also notable that Tomo appears to have less romantic interest than Yukari does. I find it nice that the characterization allows for such distinctions even in a comedy manga. 

The different portrayals of people in both Azumanga Daioh and Yotsuba&! is one of Azuma’s main strengths, enabling both entertainment and serious emotional investment in the cast.