When a hero is cursed into such a cute and adorable form, expect his chances of turning back into a human to be... pretty low. Because nobody wants to see him get out of that cute form which everyone -- the fans, in particular -- adores.
Somewhat inspired from those games and anime series where such formerly-human characters are trapped in such a cute body, and it'll be a shame to see them changed back into humans. XD
Link
Monster Tamer Billy
Now I miss playing Odin Sphere... XD