@GodGinrai:
I mean, the problem is most probably that her face was supposed to be literally "blue" (a traditional comic exaggeration of pallor as previously mentioned) and that the word was "aoi", and so the pun works in Japanese, but not Engish.
Well, I say "pun", there's some interesting things to talk about vis-a-vis the effect your language has on what colors people perceive as being "the same color" or not, but I digress.
Anyway, long story short, "looking green" does have a workably relevant meaning in English and so a more clever translation would indeed have used "green", but I think "blue" seems like it isn't actually wrong as a literal translation (as in, the color on her face if the manga were in color would most probably be blue; "blue" is the intended shade of "aoi" for her face and the rest is linguistics).