Hmmmmm all this prolonged mystery about kaori's real identity and stuff is making the fluff in this manga go down, I mean sure it would be good to know more about her but its not about her that the manga talks but of himari and mizore instead. In my opinion the author should hurry and have kaori finally reveal herself so that the fluff can continue.
Goat eyes or frog eyes. Frog yokai don't really have any connection with hypnosis so that suggests goat eyes. Traditional judeo-christian demons posses cloven hooves and the horns of a goat. This combined with her role in the manga suggests that she is either the embodiment of gluttony (Beelzebub) or the embodiment of lust (Asmodeus) or one of their servants. As Beelzebub is called "Lord of the Flies," its unlikely that she is that or one of its servants, so she is either Asmodeus or a Succubus.
@Epicredeemer Nee-san is literally Shub-Niggurath, the Black Goat of the Woods with a Thousand Young. I think Kaori-san is a bit less Lovecraftian than that.
The supernatural aside, I will say in Kaori's defense that even I
haven't changed much since I turned 14, and I am now 30 going on 31.
If I were to shave I'd look my high school photos again... -__-' Not that that's a goof thing.