Responses
he didn't find out
No one, as the MC said, the demon king has somewhat altered the results causing suspicion among the players when there is really no one who chose the Demon king in reality. This caused a greater dispute among them, lowering their guard or distracting them from what was currently happening so that the empire will weaken and the "heroes" will have less time to prepare for the real battle. - is what I think.
So... who ended up being the traitor from before??