[Reigen glances at the hand he's been dealt--three pair, not too bad--before he answers.]

It depends. Some can look human, but most of the time they opt for something more monsterous or inhuman in some manner. It's typically because they choose it in order to appear more intimidating, or they've lost too much energy, or even their own sense of self, to remember or care about what they may have looked like before they died.