I believe that the happy mask sales man is a ghost,and the the fact that he is some kind of evil immortal or something like that.And on one of the hyrulian pantheon theories that states that majora is a sun god or goddess i think that happy mask sales man is sorta of a god also.I think that he has to do something with the sun god,majora. Why does he need the majora's mask so bad? I think it is because he is trying to destroy termina. I think that majora was a god/goddess way back in ancient times and so was fierce deity and the happy mask sales man. Happy mask sales man could possible be the god of mask and after the battle of fierce deity and majora happy mask sales man trapped fierce deity into a mask and trapped majora in the mask also, and a few years later he tried to make someone wear the mask,and skull kid was the victim.