Based on her reaction I think she was aiming for letting them demonify while keeping the mood so good that people stop mind demonified demons. But that didnt seem to pan out right.
Alternatively she was manipulated into doing that. Which would kinda suck since the plot would just be kinda boringly laid out.
@PlanOfInaction before that baffled look of horror though, she had an oddly euphoric expression followed by one like waking up. Also, her ears changed shape.
If that's not a superb act, it's very possible that she's being used. There seems to be very little that can't be done with demon power's though they seem to be very specific most of the time. The fact that her powers affects the mind opens the door to others being able to as well.
Wait, so... they know that all the demonification incidents are linked to the idol but they don’t have her in custody as a potential suspect? They just figured it’d be fine and let the concert go?