YoRHa No. 2 Type B (2B) operates as a combat android within the automated YoRHa infantry, engineered for all-purpose battle against Machine Lifeforms in the 14th Machine War. Her core functions encompass close-quarters combat and ranged attacks supported by the Pod system. Officially designated a "B" (battler) model, her true classification is YoRHa No. 2 Type E (Executioner). This role compels her to observe Scanner model 9S and eliminate him should he uncover classified truths about Project YoRHa. Over numerous operations, 2B terminates 9S forty-eight times, each followed by his memory wipe. This cycle generates profound emotional conflict, as bonds form with 9S while she remains forced to carry out these despised duties, inflicting recurring pain. During missions, 2B frequently partners with 9S. Their joint operations involve assaults on Goliath-class targets, investigations into machine behavior, and encounters with key figures like the pacifistic machine Pascal and the rogue android A2. Witnessing machines exhibit human-like traits visibly disturbs 2B, challenging her assertions that machines lack genuine sentience. Key events shape her journey: confronting machine progenitors Adam and Eve, navigating the collapse of Pascal’s village, and discovering the extinction of humanity—a truth concealed by YoRHa to maintain android morale. Her relationship with 9S evolves beyond duty, marked by protectiveness and anguish. When Adam impales 9S, 2B reacts with uncharacteristic rage, vows to destroy Adam, and carries 9S to safety. Later, as a logic virus corrupts 9S, she reluctantly strangles him at his request, knowing this erases his recent memories and personality; despair surfaces as she mourns this recurring outcome. After a logic virus infiltrates YoRHa’s network, 2B is shot down during escape and becomes infected. Physically deteriorating, she encounters A2. With no backup possible due to the Bunker’s destruction, 2B transfers her sword, memories, and a final order—for Pod 042 to assist A2—before requesting a mercy killing. A2 complies, impaling her as 9S witnesses the act. Posthumously, 2B’s influence persists. Her memories and appearance manifest within 9S’s consciousness and within machine-constructed copies, often used to torment him. A2 adopts 2B’s hairstyle and fulfills her request to tell 9S to "keep being a good boy." During the tower confrontation, A2 reveals 2B’s executioner designation and history with 9S, implying his subconscious recognition of her role. In Ending E, Pods reconstruct 2B alongside A2 and 9S, restoring her body with retained memories.