It was a subtle change at first when the Damask Insurgent used an ancient artifact that cast Mashiro Temple into the darkness. The world that the women knew didn't shift quickly as Tomura had still been able to use her Ao moment's before she died.
But the longer the darkness seeped and permeated into the lands of Mashiro Temple, it became harder to cultivate Ao or even use it. Similar to a sponge, or perhaps it was the nature of darkness itself that soaked and absorbed everything available in the air.
The vast majority of the younger and unlearned Priestess were rendered helpless.
They started going down by the numbers, falling prey to the intruders that hid themselves in the darkness and with a cut of their blade ended the women's lives without any hint of remorse or hesitation.
This was their justice.
And it was bathed in blood.