I was expecting her eyes to have differing lines of color radiating out from the center, as that's how different colors appear in hazel irises, but from Page 17, it looks like her irises are composed of concentric circles. I've never seen that in an iris before.
I guess I shouldn't get hung up on something like unusual iris construction given this is manga and there are characters with other unusual geometric shapes in their irises. Even in this manga, Kurumi gets a starry cross shape in her eyes when she eats. It just caught me off-guard, expecting a her irises to be rainbow-colored and then seeing an actual, completely circular rainbow in her eyes.