They mention "Omega" in the credits. Check DarkWing-Zero's store. It might be something included in one of the packages. Look through each of her promo pages for each product. Or you can PM the artist of the image and ask them where they got them.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi