That's Eiko's picture from the FFIX Strategy Guide.
I thought that she was partially naked in that picture when I first saw it too. But if you look closely, you'll see that the pants have more pink than the skin on her face. That's why she isn't really naked, no matter how naked she might appear to be.
What's the difference then? Even if it is some kind of clothing that gives the impression of being naked, Eiko is still too young to wear something like that. Heck, EVERYBODY is too young to wear something like that.
Well, I doubt you actually got a close-up look on Eiko's sprite in FFIX. You probably weren't able to tell she looked naked by looking at her in the game on your TV screen. It's mostly just the strategy guide's fault for including a picture like that.