Hello there. While I am new, brand new even, to this site, "Freelancer," I am not new to character creation or illustration. I have a degree in studio art, and have been studying digital art for years. I can make the image in your mind a reality. We will start with rough sketches to get the poses, weapons, etc, all the little stuff just how you want it, and then I will line, ink and shade it to your liking.
I just joined this website, about an hour ago, so do not have a portfolio uploaded yet, but I did create the image you see by my name, to give you an idea. I think we could get your ninja and his arch-enemy done in a day or two. Please feel free to contact me with any questions you may have or if you would like to see more of my work.
Thanks.