Anza
I have got to say that I don't fully want to describe this as a "light blue" so much as an aqua color.
(color swatch: http://www.cosworx.com/images/sepia/LIGHTBLUE-.jpg)
And I don't fully recommend this for a Rei Ayanami wig since the color is off but the style is PERFECT for her. So perhaps doing a custom color on this wig would be best for accuracy. I do believe though that it is a great base wig to start with for many different characters.