I don't know if because of the manga with surprise tragedy endings has ruined me, but I swear the reflection in Raiha's eyes at the bottom of page 6 looks like a person hanging themselves
It's already foreshadowing that means the end is near which is sad but every good things come to an end so might as well not brood over it. I'm guessing the one who kissed him mightve been miku, itsuki, or yotsuba.
The Lack of Nino in your comment is concerning considering how hell bent she is right now to seperate herself from her sisters lol to not include her is bold.
So far as I can tell, the one that has always been talking about wanting to kiss Uesugi is Nino
The one that has been making aggresive move to Uesugi is Nino
The one that secretly hides secret from everyone is Itsuki
The one that's making best progress this arc with Uesugi is Miku
The one that come in Uesugi's mind before kissing is Miku
The one that is competing honestly with Miku is Ichika