That last page twist was great.
YES. HELL YES.
The best thing is, we had been shown before that scene from one year ago... but pretty much everyone here had forgotten about it, haha. Well, at least I myself had completely forgotten. :P
So we knew that Kurumi had first fallen in love with Nikaidou at a time when they were both at a café, one year ago. In that flashback, Kurumi was looking at Nikaidou (who was dressed up really cute) crying all alone at the neighboring table. We weren't told exactly what had happened, but we later found (through Nikaidou's inner monologue) that Nikaidou had confessed to Jun and had been rejected more or less at the time of Kurumi's flashback...
... so, putting two and two together, it wouldn't have been difficult to come to the conclusion that Kurumi's flashback scene at the café was of the time when she had witnessed Nikaidou's confession/rejection scene. And thus, she knew perfectly well what was going on with Nikaidou and why she had become a "loose girl" after that.
But I guess nobody in this forum can add two and two, myself included. Doh.
I wonder what face Kyou-chan would make if she knew that, even if she had told Kurumi all the "dirt" she had on Nikaidou, Kurumi would just have said: "Yes, I knew already. I know what's going on. I know more than you. Don't worry, I'll be fine."
Nobody really expected it. This was a masterful twist alright.