Now wtf did I just watch?
Story was seriously weird and seemed incoherent, too.
First some girl we know nothing about is dead, and there are lots of destroyed buildings. Two years back, the same girl is barely saved by one of the two main heroines doing a suicide attack, saving her and the city. Going back, she's still alive, and no destroyed buildings.
So what we saw at the beginning (dead Hibiki and destroyed buildings) is what would've happened if Kanade wouldn't have saved the girl and the city with her suicide attack. The show could be showing several possible realities to screw with our minds
It could be showing one (dead Hibiki and destroyed buildings) where Kanade is still alive because she didn't use her suicide attack, and another where she did, Hibiki survived, no destroyed buildings, and then Hibiki takes her place.
Then they could be switching back and forth between these two realities. Or, they could add some more diverging realities to the mix, for even more mindrape...