I'm trying to get the "Immortal Photobomb" achievement, but I never paid attention to the fact that Gentiana could be in Prompto's photos until now.
However, I've already completed the main story and am at Chapter 15.
My question is: Can Gentiana appear on random photos at chapter 15 (that is, after I've completed the main story?
—EDIT— I finally got it at chapter 15 so I confirm that this trophy cannot be missed.
Best Answer
Yes, it's possible to get this achievement at any point after meeting Gentiana.
From this achievement guide:
Others have confirmed that you can get this achievement after completing this game. See this thread:
(emphasis mine)
From personal experience, I believe I've gotten at least one Immortal Photobomb-eligible picture (though I got the trophy quite early on) after completing the game, during my trophy cleanup.