@Crash21
She's Tsukina Farrow, but I don't think we get to know her more, except that she is Tokikaze's wife and gives a digital ball to Hina before getting absorbed to the abyss.
@Crash21 Not that one. Rihito said she was "their" childhood friend (probably his and Tokikaze's). Besides, his classmates were left behind and all committed suicide anyway...
his mother is the ones that love rihito in the past, his classmates that always trying to make rihito back
the ones that always try to seduce rihito before