First of all, Aya and Koga are so cute in the concert hahaha
And for the new girl, since we have so little and to avoid a Narita case(?; in which a lot of us (yeap me included) thought he was a bad guy, to end the opposite~ I will just write what got my attention and theorize just because I can(?:
1- How they call each other, Kanna just "Mitsuki" but Koga her name with "-san"; so two options for me is, that Kanna is indeed older than Koga and Aya but I don't think too much (can totally wrong of course, and in this I will not mention the cigarette). Or two, is just Koga way to call people, so not to get "so close".
2- The face of Koga is one of shock, but how already told by in some comments, it can be just be a surprise of the moment. So left to see next if she will be happy or not to see Kanna.
3- Kanna towards Koga seems happy to see her, not only the smile, the way she called her with intensity and the "happy" comment?, I will call it that because dont know another expression~ that she looks cooler now.
But after that, we got an off panel of her changing her attention to Aya, "a friend?"; to next see Kanna dropping the smile.... So yeah, ahother thing I will keep thinking until next Sunday hahaha
4- Last one I promise hahaha (for now tho!). The actual conflict of the manga, tho named a good few times the "career paper" situation, I glad we are going a even little back to "why mitsuki is like this at school" (I know some things here but let keep them aside, until we are all free of spoilers(? ). That said, tho difficult, I think it's a good idea if the two things can be aborded like "one" (being the center the two "modes" Mitsuki has); since it could be seen separately but having a character like Kanna maybe it will be a 2x1(?