About New Game+

[DemonslayerRyuu]

It turns out I missed Shigure using his Mystic Arte during my first encounter with him at the mine. I know it doesn’t count when does do it to end the battle. He has to do it during that battle. Now I was wondering this all the Mystic Artes I have in my first playthrough carry over to New Game+ or must I see them all again?

[Three-Snap]

I can’t personally say if you can.  But the witness the mystic trophy guide says this in the first paragraph.

 

View every single Mystic Arte from both enemies and allies to earn this trophy. While you can pull off your party members' Mystic Artes at any time, you only have one chance for the enemies as once you have finished their battles and missed to see their Mystic Arte, you have to try again on another playthrough to see it. Fortunately, you do not have to see all Mystic Arte within a single playthrough, so any Mystic Arte you already saw will count as seen when you start a new playthrough with New Game+. There is no ingame checklist for this trophy, so you have to note down yourself which you have seen already.