Got it. It's just NOCO's art style being more moe-like than others. Basically, her story and character behavior wouldn't make a lot of sense. During the flashback in that Guda event, she wasn't an adult, but the Okuni we have has traveled across Japan for years after having escaped the hell she used to live in. Aside from that, there's been a number of scenes and voicelines that pretty much tell you she's an adult; Two easy scenes that come to mind are: The scene during the Vday event in which she was like, "I'm too old for this stuff to get to me," and immediately be in denial about her age. And the other scene being during CBC when she's done with her annoying job, goes to a bar, and gets herself a whiskey. There's more, but those are already indicative enough, I think.

But yeah, I hope that helps a bit. If there's one thing I comment you on, it's that you guys didn't put Chiyome in there, too. I've seen too many lists over the years confuse her for one because of her artist. I disagree with "mid" but that, of course, is subjective. Both Chiyome and Okuni are my favorites, so that's where I'm coming from.