You
Flower
Charlie
Prof
Melkor
Indigo
Those were the four people who participated in the 4th trivia. All of you say you didn't win it. Which means, because someone won it, one of you must be lying. Moreover, given the names there, it's almost certain that they were told the right answer from their scum group.
Tohru used an ultimate ability to kill. However, we know Melkor is Wendy, and Flower is Milim. Which means for Tohru to be there, it would have to be one of the 4 left. You, Prof and Charlie all had kills fails on them because you are not dragons. Thus, either Indigo is Tohru, which is possible or Tohru is not in that group, and unlocked their ultimate via ither means.
Objectively, we lynch Indigo, but I am hoping he will claim more information, and Charlie has been a scum read of mine all game, hence my vote there currently.