A group of Alices, one mother and several children, are tortured and killed by an Anon, using several kitchen and cleaning appliances, here is brief synopsis post #1488.
While it wasn't left clear in the synopsis if this are part or decendants of that group or not, it is said that this all started when a gang of Raper Alices Raped to Death a Pet Reimu, making the owner of that pet develop as much hate for Alice as he had love for Reimu.
And being honest, there are way other stories on which Alices are only victims not rapers, this is very confusing out of lack of translation or a more detailed summary.
Maybe one of our Summary Guys could check the story pages that are linked in the synopsis of the pool and see if this were part and decendants of the original rapers of if anon just grew to hate all Alices in general.