Episode 8 of Shingeki! Kyojin Chuugakkou features this ghostly character, who is not addressed by name during the episode:
Who is this supposed to be?
From reading the cast credits, I see that this person's name is probably フリーダ ("Frieda"?). Should I know who that is from having watched the anime (not Chuugakkou; the main one, which culminates with the female titan arc)? If not, please please please use spoiler tags - I've been religiously avoiding spoilers for the show for three years now in anticipation of season two, and would rather not break my streak.