Granblue Fantasy has been doing really well for Cygames, both online and for their mobile app. The company is coming on on the game's 4th Anniversary and to help celebrate, they've managed to put together a collaboration with Atlus to bring Persona 5 into the mix. During an exclusive livestream, the company revealed that there will be a new event in June revolving around the JRPG as the two companies will collaborate to bring some kind of Persona 5 related materials to the game.
There weren't a lot of details revealed during the stream, but these two promotional photos were released along with the announcement, showing off Morgana and the Protagonist as part of the promotion, but not much else. We probably won't get the full details until around May, but best guess, we're probably going to see characters from the game be playable within the Granblue Fantasy universe.