These are wonderful!!! Are you serious?
You have done a beautiful job laying down the color but to bring these to a more complete level, you need to continue working from these colorings. Right now you have these wonderful base colorings, but they need shadows and highlights to elevate them and give them more depth.
I adore these so much - I would love to see you keep working on them!
Try to imagine a light source in play here. For example, in the final Moon and Mask panel, their faces should have a glow of sorts from the moonlight. Mamoru's right side of the face should be cast in darker shadow with the left side having a few plays of light against his cheeks. Remember, the human body is round so light curves around the face, arms, the knuckles of the fingers and so forth. Fabric also catches the light in the folds of the creases. These subtle little aspects will completely transform your pieces.
Remember: SUBTLETY! Always gradually build up your highlights and shadows.
For the backgrounds, you can also apply gradient layers so the sky, for example, is not a single flat blue color. Even the night sky has very subtle changes in the shades of black or darkness.
If you would like, I have some fabulous manga coloring tutorials that I could send you for tips and references if you are searching.
Can't wait to see what you come up with! Please continue to update us!