I've been working on a long post about Kaori, John, and their relation to Sekai and Wires that I'll hopefully have finished tonight or tomorrow, but I'll add a couple things about this event now.
As you alluded to, the opening conversation seems to happen under a purple moon, which Kaori is looking at when Sensei arrives.
Then she has the speech about the end of time, etc. which seems to be somebody else talking through her, given the content and the lack of Kaori-isms. Right before hand, a Girl Who Cannot Breathe poem is flashed on the screen
That would seem to indicate it's SeKaori talking, but I feel there's more going on. In other events SeKaori is accompanied by a red glow, not purple, and Kaori's eyes also don't change here. And I could be wrong, but the "troublesome girl" line especially doesn't sound like Sekai to me.
I don't know what's going on with Kaori's disappearance, but given the blackouts are connected to Wires losing power, it seems unlikely to be something he was able to cause (at least intentionally).
At the end of the event, Sensei returns home and the render is upside down
I think this could indicate the upside-down house is involved in this event. Could the purple moon be an upside-down house symbol? We already have one purple connection with the emphasis on lavender.