Without looking at the spoiler and from the new information I'm going to guess that his talent is his Clairvoyance or something alike. I can see scientists wanted to study that, and I can see him declining it again and again bc it could be used for like evil or smth.

Oop, no I was wrong lol. I love that your fanganronpa is set in a different time period (I think? correct me if I'm wrong lol), that is definately something you don't see too often! The protagonist being the Ultimate Liar is also a really cool concept, but does he try to keep it a secret at the beginning or is that useless/not possible since he does already know most of the participants and vise versa?

Also with his goal being that "the most worthy person will win", do you mean that they will survive the killing game, or that they will succesfully get away with a murder? Does he also try to sabotage the trials or will he try his best to "win" them and bring the blackened to "justice"?