My favourite is Yuri actually, need more of her.
Let's see...
The first cover was the succubi and the story mostly revolved around Sou's interaction with his family.
Second cover had Team E, with a prominent Miku plus Kanaria and Hinata in the back... a lot revolved around them
The third cover featured Kaede who started the class exchange, plus Aya and Hana - we got to see them plenty.
Now, then... let's take a good, long look at the upcoming forth cover.
Compared to the prior three, this cover is special - it continues to present us, let call it a featured girl (in large), this time we get Yuri. BUT this cover breaks the three girls template without completely changing it. Instead of two other "heroines" Yuri is partnered with her current splits. So, if that cover more or less shows who will play a major role in the following arc, then you can expect to see your wish come true to a certain degree.