That was my thought as well. The fact he wears looser clothing does not help either. I will be trying to define his muscles more when I go back and redraw the sprites to see if it will help.
So after doing some concept sketches and redrawing Yukine's sprite. I absolutely see what you mean. Both myself and my team have agreed we will overhaul all the sprites. It will take some time so we won't have them ready until maybe day 4, but we will definitely be doing it.