Forgive my ignorance, but what are they talking about?
Kae is talking about a part of their past Inori doesn't remember.
@Soen Kai: Ah, thank you. I thought it was that. Its just I didn't read Vol .2 which was summarized but I didn't find where to read it or something like that...
=) What do you mean? Vol.2 is still able to be purchased in English at the publisher's.
I even made a how-to, because the page is German.