Popola

Popola is the younger twin sister of Devola, they are the overseers of Nier's village. Pretty, with a sweet voice and friendly demeanor, she is a heart breaker. Numerous letters are sent for her at the library, asking for her heart, but none have ever received a positive response. She is very fond of Nier and Yonah.

It is later revealed that both Popola and her sister Devola are android observers for Project Gestalt.

NieR:Automata:

New models of the twins exist thousands of years after the events of NieR. After the death of the Shadowlord, the original Devola and Popola models were blamed for the failure of Project Gestalt, and in turn the remaining models were reprogrammed to harbor constant feelings of guilt.