He claims he's interested in the field out of a genuine desire to understand and undo the damage wrought by our mystery perpetrator. His words, his expressions, everything is either perfectly performed or sincere.

[The weight of Akechi's words suggests he believes equally in either possibility.]

He's quite a fan of the Phantom Thieves, too. I've known enough liars in my lifetime to deduce that at least some of his feelings are genuine. Every meeting with him, I'm constantly observing the minutiae of his words, his body language, everything.