The Sisters are clones derived from the DNA of Academy City's Level 5 electromaster esper, Misaka Mikoto. Their genesis lies in the Radio Noise Project, which sought to mass-produce Mikoto's clones for military purposes. Initial attempts failed to replicate her Level 5 abilities, yielding clones possessing only Level 2-3 electromaster powers, leading to the project's temporary suspension. Approximately 20,000 clones were repurposed for the Level 6 Shift Project. This experiment required Accelerator, Academy City's strongest Level 5 esper, to kill all clones in combat to theoretically attain Level 6. Tree Diagram calculations determined that eliminating 20,000 lower-level clones substituted for killing Mikoto herself 128 times. The clones participated under the belief their existence held no intrinsic value, frequently describing themselves as expendable. Each clone bears a numerical designation (e.g., Misaka 10032) and shares Mikoto's physical appearance, distinguished primarily by specialized goggles enabling electromagnetic phenomena visualization. Physically matured to adolescence rapidly within incubation tanks, their mental development depended on the Testament machine implanting knowledge, motor skills, and basic emotional frameworks. Despite this, emotional expression remained subdued, and they communicated in a distinct third-person style, often verbalizing actions and emotional states. Their shared esper ability, Radio Noise, granted electromaster powers and facilitated a unique Electronic Telepathy network – the Misaka Network. This network enabled instantaneous memory, experience, and computational resource sharing among all clones, functioning like a hive mind while preserving individual consciousness. Following the Level 6 Shift Project's termination after Accelerator's defeat by Kamijou Touma, surviving clones dispersed across research facilities for medical treatment. Their accelerated growth shortened lifespans, necessitating hormone balance adjustments to normalize aging. Post-experiment, the clones began developing greater individuality and emotional depth. Exposure to positive interactions, particularly Touma's intervention, fostered sentiments like affection and gratitude toward him among many. They also started exhibiting preferences, such as appreciating Gekota merchandise, and engaging in subtle rivalries. The network evolved a collective consciousness known as the "Will of the Whole Misaka Network." This distinct entity, separate from individual clones, could influence their actions and occasionally manifest through them, displaying a broader emotional range and independent interests. Among notable individual clones, Last Order (Designation 20001) serves as the administrative controller of the Misaka Network. Created as a fail-safe, she possesses a more expressive, energetic personality, often acting childlike despite her critical role. Another distinct clone, Misaka WORST, operates with significant network autonomy. Engineered for higher combat proficiency (Level 4), she exhibits pronounced tsundere traits and independent decision-making. Within the "A Certain Scientific Accelerator" storyline, the Sisters' network proves crucial to Accelerator's recovery after a severe head injury. Medical personnel connect his brain functions to the network to compensate for impaired calculation abilities, enabling him to utilize his vector manipulation power at roughly half capacity via an external electrode. The network also provides computational support in crises, such as calculating complex defense system trajectories during external threats. Accelerator develops a protective bond primarily with Last Order, who frequently seeks his company. This dynamic extends to the broader network, as Accelerator increasingly acts to safeguard the clones from targeting organizations like Disciplinary Action (DA).