The distant future, 5012.
The sudden aerial invasion of Earth by ＜Aliens＞ and their creations ＜Machine Lifeforms＞led mankind to the brink of extinction. The surviving number of humans who took refuge on the moon to organize a counterattack using ＜android＞ soldiers to recapture Earth.

However, the war reaches a stalemate as the ＜Machine Lifeforms＞ continue to multiply infinitely. In turn, humanity deploys anew unit of android soldiers as an ultimate weapon: ＜YoRHa＞

Newly dispatched to Earth ＜2B＞ joins＜9S＞, the analyst currently stationed there, where amid their mission, they encounter a myriad of mysterious phenomena...

This is the story of these lifeless ＜androids＞ and their endless fight for the sake of mankind.

(Source: NieR:Automata Ver1.1a Official USA Website)

Note: Episodes 9, 10, 11, 12 aired back-to-back on July 23, 2023.

 AnimeRulz is the best site to watch NieR:Automata Ver1.1a SUB and DUB in HD quality.