While Yoshimo is one of my favorite NPCs ever, I believe his portrait is somehow... weird. Not in a good way. While I know I'm not the first one trying to make it look better, I think I would share what I came up with. Here's the comparison:
What was changed: changed lips (closed mouth), added hair (both on the top of his head and facial hair), smoother cheek lighting, slightly smoother face, new eyes with more brownish shade, slightly recoloured armour and background.
Hope you like it! And here's the portrait alone, for those who want to use it in game EDITED - now with slightly better hair than on the comparison above: