It is interesting to note that whoever it is, Papalymo knows. What kind of person he regrets giving the mask to, or would even be willing to help conceal the identity of in the first place, could potentially shake up the contenders a bit. However, since Papalymo knows, I would assume that any two-bit character is out of the question. It is either one of the current two main speculations, or someone from Yda's past (the King of Ruin? unlikely. Her relative, or the lost prince? I digress).