9S, formally designated YoRHa No.9 Type S, is a male-model android and a core member of the elite automated infantry unit YoRHa. As a Scanner-type unit, he is designed for reconnaissance, intelligence gathering, infiltration, and electronic warfare rather than frontline combat. He has the appearance of a young boy with light skin and silvery-white hair, typically dressed in a black military-style coat, shorts, and boots, and almost always wears a black blindfold-like combat visor that does not impair his vision. His personality is marked by profound curiosity, emotional expressiveness, kindness, and a polite, friendly demeanor—traits somewhat uncommon among androids expected to suppress their feelings. He is sociable, often shows compassion to non-hostile machine lifeforms, and appreciates human experiences that are functionally useless to an android, such as the simple pleasure of taking a bath. His primary motivation begins as a desire to serve YoRHa and the memory of humanity, but his bond with his partner, 2B, quickly becomes his central priority. In the story of NieR:Automata Ver 1.1a, he is deployed to Earth alongside 2B, a Battle-type android, to assist the local Resistance and reclaim the planet from machine lifeforms. His role is to provide tactical support, hack enemy systems, and uncover critical intelligence. The most pivotal relationship in his existence is with 2B, which is tragically complicated by the fact that 2B is secretly an Executioner model tasked with eliminating 9S whenever he learns forbidden truths about YoRHa and humanity. This cycle has played out many times, with 9S being killed and reset, though he sometimes chooses to sacrifice himself to spare her pain. Other key relationships include the Commander of YoRHa, the rogue android A2, and his support pods Pod 042 and Pod 153. 9S undergoes a profound and tragic transformation: he begins as a cheerful, inquisitive, and somewhat naive scout, but after witnessing what he interprets as 2B’s death, his grief and hatred consume him, turning his gentle demeanor into a ruthless, violent, and self-destructive obsession with revenge. In terms of abilities, he possesses unparalleled hacking proficiency, allowing him to remotely infiltrate enemy systems, disable defenses, take control of enemy units, or destroy foes from within. He is also a capable sword fighter, typically wielding a katana, and uses a floating support pod for ranged attacks. His scanner model grants him enhanced physical capabilities, including superhuman speed, durability, and the ability to manipulate objects via magnetic levitation.