TV Special
Description
Satsuki Kiryūin is the firstborn daughter of Ragyō Kiryūin and Sōichirō Kiryūin. At age five, her father revealed Ragyō's true nature as an entity fused with alien Life Fibers and her plan to exterminate humanity, including the fate of Satsuki's infant sister Ryūko Matoi, who underwent fatal Life Fiber experiments. Sōichirō faked Ryūko's death and disappeared to lead a rebellion, leaving Satsuki to covertly prepare for a future uprising against her mother.

During her childhood, Satsuki recruited allies to build her resistance force. Her childhood friend Nonon Jakuzure joined after intuiting her resolve. In middle school, she recruited Uzu Sanageyama by defeating him in combat, Ira Gamagōri by testing his protective instincts, and Hōka Inumuta for his hacking skills. These four formed her "Elite Four." She later established Honnōji Academy as its Student Council President, using it as a training ground for an army against Life Fibers. She issued Goku Uniforms—clothing woven with Life Fibers granting superhuman abilities—to enforce a meritocratic hierarchy where students competed violently for status. This system aimed to strengthen humanity for the coming conflict, resulting in harsh subjugation and casualties among dissenters.

Satsuki initially positioned herself as Ryūko Matoi's antagonist when Ryūko arrived at Honnōji seeking her father's killer. She manipulated Ryūko into battling her forces, using these conflicts to evaluate Ryūko's potential as an ally. To counter Ryūko's Kamui Senketsu (a sentient uniform of pure Life Fibers), Satsuki claimed Junketsu, another Kamui intended as her "wedding dress." Unlike Ryūko, Satsuki felt no shame in Junketsu's revealing form, enabling full synchronization through sheer willpower. Her primary weapon was the Life Fiber-cutting blade Bakuzan, later reforged into dual swords (Bakuzan Gako and Bakuzan Kōryu) after its destruction. She also concealed false toenails made of Bakuzan's material as emergency weapons.

After years of preparation, Satsuki launched her rebellion during Ragyō's invasion of Honnōji, stabbing her mother and declaring her true objective: to avenge her father and sister. This failed, leading to her capture and torture. Rescued by the Elite Four, she discovered Ryūko was her surviving sister and later helped Ryūko break free from Ragyō's brainwashing by temporarily wearing Senketsu. Post-capture, Satsuki acknowledged the cruelty of her methods and apologized to Ryūko, signaling her shift from dictator to ally. She fought alongside Ryūko in the final battle against Ragyō and the Primordial Life Fiber, contributing strategies and combat support.

Following Ragyō's defeat, Satsuki cut her hair short as a gesture of change and enrolled in Rinne High School. Her personality, previously defined by ruthless pragmatism and regal authority, softened, revealing moments of warmth and protectiveness toward her allies and sister. In the spin-off game *Kill la Kill the Game: IF*, she features as the protagonist in an original "what if" storyline diverging from the anime, wearing a new Kamui variant, Jinketsu Shinzui.

Her abilities included superhuman strength, speed, and tactical genius. She resisted Junketsu's parasitic control through sheer resolve and could generate light or shockwaves through force of will. Her leadership inspired unwavering loyalty, though her initial rule exploited fear and discipline.