Comparing current Natsu to your older version from last page, I gotta say that the chest is better on the old one, simply because it is simplier, has less detail and doesn't blurr that much. New version uses gold outline and skin, which kinda belnds together, making it hard to see what it is.
Other advice I have for pretty much all the sprites, is to keep the hair less chaotic. Right now it has highlights all over the place, dark outlines too. Try keeping it simple. Good work on these nonetheless, good to see you back and at it