It's listed as requesting critique, so here it goes The pencil marks of the outside circle would look better if they were a bit more erased or colored in (like in the right of the circle.) The transitions of color in the background right above her head and to her right could be more gradual. Also, although it looks lovely in purple and black, Pluto's hair color is usually green. It's a gorgeous piece I love the detail and the color combinations in it. Also, the shadows and highlights in it are lovely.
Uh, I just realized now that it is in A5...!!! It's AMAZING how you are able to make it so detailed in such a small size - I especially love with their eyes, so alive and beautiful! And Setsuna is really beautiful and serious, also has a touch os mystery to her - perfect! I think she is the best , most fitting Setsuna I've ever seen (even including the original series XP)