Apartment
[Even if they've got a new Kuran in the apartment and two neighbor boys that her parents have seem to adopted, Ai is still going to school today. It's only for a single class today and it isn't until the afternoon.
So when the appointed time to leave comes, she's gathered up her homework and other supplies - all packed neatly in her bag and sets out. Only to be stopped on the stairs by a familiar and yet new scent. Ai's eyes widen at the sight of what is obviously someone from the Kiryuu family who also happens to smell like a Kuran.
Is this... the future? So far everyone here from their world has been from Ai's past and she was the one from the future - no matter who was here. Until now. There has never been a person with the blood of a Kiryuu and a Kuran in history as far as she knows which means this person is... her brother?
Maybe he notices the very small difference between the sister he knows and the one standing here, it isn't much but her hair is shorter than he knows. It only comes down to her shoulders even with it still up in the ponytail her mother had given her while making breakfast.]
You're...
[Congrats, big sister is actually at a loss for words.]