Written by Yoko Taro, YoRHa is a stage play which tells of the events before NieR:Automata. Taking place in 11,941, it tells the story of the Pearl Harbor Descent Mission during the 14th Machine War. 
During the 14th Machine Armament War in the year 11,939AD, humans are near extinction. With the invasion of the “Living Machines”, humanity had no choice but to abandon the planet, taking refuge upon the Moon. Their only hope lies in an armada of specially configured androids called “YoRHa”. Programmed with human emotions and feelings, they descend upon the surface of the planet to combat the ceaseless onslaught of the Machines.
With the destruction of No1 in the descent to the planet, No2 assumes command over all units… however reluctant and unsure of her own abilities. She remains this way throughout the entirety of the play; she keeps her black “visor” on the longest…only taking it off in the final scene when she faces the machines on her own.
After witnessing the destruction of her unit and the last of the Resistance, a failed android expedition hundreds of years before her time, No2 is alone among a cold, unfeeling world ruled by machines.