Oh Kirigiri…still keeping up with the mysterious act. So…based on the mask, is the sixteenth student the one who knocked Naegi out in the hidden room? If so, it’s possible that this person isn’t actually working for Monokuma. But who killed her? It probably wasn’t Kirigiri…she was likely discovering some big secret.
But…why do the painted nails seem like an important clue? Knowing the style of this show, I would assume that the sixteenth student had to be someone who was with the group the whole time. This would allow one of the original fifteen to be the one who murdered the sixteenth…but…who was it?