Asuka Langley Soryu
Anno required a "gloomy", "cool character with short hair", so Sadamoto designed Rei originally as a brunette with dark eyes; however, it was necessary to distinguish her from the other female protagonist Asuka Langley Soryu, so he designed her with eye and hair colors opposite to Asuka's. He also published a drawing of a dark-haired character named Yui Ichijō among Rei's designs in one of his artbooks, without specifying whether it is an early conception of Yui Ikari or not. While Asuka was conceived as "an idol-like figure" in "Neon Genesis Evangelion" and a symbol of "heterosexual desire", Sadamoto designed Rei as a motherhood symbol, thinking of her as "the Yin opposed to Asuka". Anno also suggested that Rei's eye color be red, a feature he believed would give her more personality and distinguish her design from those of the other characters. Her hair color changed to blue, similarly to the main character from "Aoki Uru", the movie sequel to "The Wings of Honneamise" which was never made. Sadamoto also gave her black stockings, inspired by a women's handball team he saw playing when he was in middle school. Black allowed him to differentiate her from the characters of the series released in the same period and go against their trend.