Ok. So, hear me out.
I had this silly dumb half-joking "theory" for a while that Aina is going to turn out to be Matoi's great-great-great-grand-daughter. This is based on the obvious element that she has the same hair/eye colour as young-Matoi (Prior to her getting temporarily falz'd and then thrown into the future which turned her hair white).
But also that the introduction of NGS, is a narrative reversal of PSO2; a young ARKS trainee stumbles across a stranger with amnesia, who turns out to be a great hero of ARKS past. In the first game you are the trainee, Matoi is the hero. in NGS, Aina is the trainee, and you are the amnesiac hero.
Anyway, I posited this theory jokingly to my alliance-mates, who said "But Matoi has always had silver hair hasn't she?", which got me doubting my own memory, so I went and dug around for a picture from the in-game cinematics to prove to myself as much as anything that I was right. Then it struck me...
...Aina looks less like a distant relative of Matoi's, and more like young-Matoi with an NGS makeover.
Is there bizarro-world timey-wimeyness shenanigans going on here? (Probably not, but I don't think the similarity is coincidental. Wouldn't be surprised if Aina and family are descendants)