Anon is a manager of a yukkuri clan on a mountain, he occasionally sedates them to give them drugs to keep their numbers in line, but this time, he intends to abuse them.
He starts by crippling the clan while they're sedated, then begins once they're awake.
Reimu-Marisa: Rips out their three children, and shows the babies to the parents before crushing them.
Marisa-Alice: After extracting the premature yukkuri from Marisa, Alice goes crazy and rips them to pieces saying they're not city-sect, and Marisa goes insane as well.
Single Mother Reimu: He injects it with Remirya cream, and the Remirya grows, devours the other children and the mother.
Anon goes down the list, eating some, forcing some baby Alices to refresh. The final Reimu-Marisa pair, he forces the Marisa to damage its mate so as to save their unborn children. He then tells them they can have children now and leaves.
Since then, the clan is suffering. Mothers lost their children, or lost their ability to have any. Child stealing occurs. And as for the last yukkuri couple, the Reimu that sacrificed so much for its children faces rejection and hatred from them, and eventually crushes its children without realizing it.
Nobody here but us chickens!