So this arc is shaping up to be uncharacteristically intricate.
Subplots:
1. Aine and Cro.
This plotline has been going on for some time and with the new context in the last few updates, it seems to me that getting a 6th Goddess isn't out of the question at this point. Tsukiko says that a Goddess is the sum of her parts (shards). We have a lot of compatible shards to make a new one. Cro, Aine, Kieran, Mizaki, potentially the lost fairy sisters and possibly Kieran's siblings.
2. Aine and her lost fairy sisters.
So now both MC and Keiran have seen what seems to be Aine's fairy sister. I'm not 100% sure that it's actually a sister and not something more complex, like Aine's initial form, or even a shard if that's applicable, but for all intends and purposes, she is a new and unexplored character.
3. Kieran's bonding.
I have the distinct sense that there isn't a single reliable narrator on this issue. The explanations are way too abstract, the "control" aspect isn't exactly explained, and the size of Cro's absence doesn't seem measurable, so if Aine can fill it.. I supposed that there are more things that can fill it.
4. Kieran and Ashley.
I bet that Keiran's pep talk is foreshadowing.
- The only one who managed to unlock Ashley's powers so far, is Cro.
- Keiran is still touched by Cro even if she isn't possessed anymore.
- In Auxo's flashback Mizaki and Ashley were twins.
So I expect that when Kieran and Ashley train together, something very interesting will happen.
5. Kieran and her sisters.
Considering how much drama the game builds in this relationship, I think it will turn out bigger than it seems. I actually wouldn't be surprised if almost everyone in Kei's line is related to Hebe in an important manner, considering that Kei herself has the blue-green eyes. It would also be ironic that half of Asshole Grandpa's line would be touched by a Goddess.
Additionally the game brought back the Cursed Girl (which looks like Stacey to me) and the older CJ-Looking bandana biker guy who seems to have some relationship with Ruriko.