I personally don’t believe that this is the face of a child. Anime faces (especially female ones) can be very ambiguous and age is usually told via the characters voice and mannerisms, unless the faces are very exaggerated in such a way that it is unmistakably a child or adult. Due to Nagatoro’s mannerisms and voice, as well as the kinds of faces she pulls in the manga, I just can’t imagine her face as a young child’s.

That said, the horny comments make me uncomfortable, and this is regardless of Nagatoro’s face and body type. Like, show some restraint, would ya? It doesn’t help that while Nagatoro may be 17-18 (I think?), that is still someone very youthful. Comments like that would be discomforting regardless of both the speaker’s and the subjects ages.