If you saw the prequels, then this is continuing the story you already know and love. It starts out a few months after Yuuki Yuuna wa Yuusha de Aru finishes, with all the same energy of the Hero Club as before, and trust me Studio Gokumi wastes no time getting us into the next exciting chapter of the story.
This time around the story is a little bit darker for reasons I do not what to mention because spoilers! Sufficed to say given the 2 prequels we know a lot more about the world, and this season is doing a great job of building on that,
while still keeping everything we know relevant.
The danger this time seems like its going to be on a different level from the prequels. While the Vertex are still very much alive and kicking, I'm happy to report that they do not seem to be the main focus of this season. So, I'm very excited to see what Studio Gokumi has in store for us!