I really enjoyed this. I think Kurumi grew closer to Moe by reading all her manga, which was very personal and contained her true feelings. In both mix and this Moe isn't very good at expressing herself to other people, the reason she's so embarrassed when Kurumi reads them is because she'd never dare saying it directly to her.
With that in mind I picture that they did have mutual feelings for each-other in high school but Kurumi didn't realise that Moe did too. After she becomes an idol on a whim she tries to find what her crush is doing (Remembering that Moe wanted to be a mangaka). And then finds how much she meant to Moe with everything being about her. She takes some time to sort out her feelings, it said they took 4 or so years apart but when you think that this could be career damaging for Kurumi, not just having a relationship as an idol but with a girl too.
I guess she made the fake persona so she could just be herself and act the way her feelings want to. Anyway after Moe releases the doujin about her feelings for Kurumi in high school it gives Kurumi the courage to talk to her openly, she knows now that she hasn't misunderstood anything and after Moe puts herself out there she can hardly continue trying to hide how she feels and who she is. All of Moe's other work has been about IdolKurumi, so I think its safe to say she still was carrying feelings for her before the get-together. The rest is history!
I think I might have got carried away there... But I seriously love Jin's work and she often leaves subtleties rather than outright stating things. (Though some of this is also interpretation)
