Satsuki Kiryūin

Satsuki Kiryuin is the president of Honnoji Academy's Student Council and the first antagonist in the anime Kill La Kill, but later becoming a deuteragonist after her plans to overthrow her mother's Life Fiber fashion industry came to fruition.

She is later revealed to be the sister of Ryuko and the two join forces in order to defeat Ragyo in the climactic battle against the Life Fibers, who sought to enslave and destroy the human race.

Appearance
Satsuki is a tall slim woman with an angular face similar to her mothers with long dark blue hair and blue eyes. She has rather thick eyebrows and a rather large bust. At the end of the series she cuts her formerly long hair to shoulder length in page boy style.

History
Satsuki was the first born child to Ragyō and Sōchirō Kiryūin, and soon became the first failed test subject of being fused with Life Fibers. However, after Sōichirō learned the truth about Ragyō, he knew that he would be punished if he betrayed her. He secretly taught a 5-year-old Satsuki about her mother and the secrets of Life Fibers. He then revealed that Junketsu will be her "wedding dress" before he took an infant Ryūko with him into hiding.

Personality
Prideful to say the least, Satsuki is extremely intelligent, calculating, patient, while simultaneously unwavering and iron-fisted. Unlike with Ryūko and Senketsu, she had no shame in wearing the Kamui Junketsu in its most revealing form; she claims that her actions in donning Junketsu are, like the Kamui's name implies, "utterly pure". In the beginning of the anime, Satsuki refers to people as "pigs in human clothing," and justifies that the weak and foolish must be ruled. Due to her steadfast convictions, she also possess a natural charisma and ability to lead others. In spite of her pride, Satsuki is shown to be pragmatic and determined, willing to cast aside pride and using whatever means necessary in order to secure victory, even if it threatens her life. When fighting Ragyō, Satsuki noted that her willingness to fight her mother and the Life Fibers was due to revenge, noting that great causes are born from personal desires.

In spite of her behavior at school, Satsuki is not heartless. While very harsh and not very willing to tolerate failures, she does care a great deal for the Elite Four; and is as protective of them (in her own hidden ways) as they are to her. As a child, she would always drink Soroi's tea in order to protect his feelings; despite disliking its bitterness for a long time, she eventually found it delicious. When she reminisces about this to Soroi, Satsuki herself notes that she must have been a kind-hearted girl if she'd gone that far to protect her butler's feelings.

Satsuki genuinely loved her father and her sister, enough to avenge them by attacking the mother who disposed of them. Likewise, despite a bitter, almost hatred-fueled rivalry with Ryūko for most of the series, Satsuki noticeably softens up to her when she learns that Ryūko is the sister she'd long believed to be dead.

After the attack on the S.S. Naked Sol in Episode 22, Satsuki allows Ryūko, still synchronized with Senketsu, to punch her, although the Elite Four protect her by standing in the way. After explaining the reasons for her actions to Ryūko, Satsuki calls herself a fool; she states that she cannot hope to win against Ragyō by employing her cruel methods—which include manipulating and using one's own family. Satsuki finally sees that the world's beauty comes not from being "cut from the same cloth", but from the innumerable, unexplainable things that the world overflows with. She asks Ryūko to help her fight to protect that "beautiful world"; upon saying her part, Satsuki bows to Ryūko—a shocking sign of sincerity. Though Ryūko tries to stay angry at her, this uncharacteristic act convinces her to let her anger go.

After this, Satsuki becomes a bit more open and relatable to others. She shows this when the gang has a celebratory dinner of Sukuyo Mankanshoku's signature croquettes, when she agrees with Mako about their being delicious; and when Nonon and Uzu have an argument involving disrespect (Nonon) and lack of tact (Uzu), telling Ira that hearing them bicker "makes it feel that I've truly come home". She also refers to Mikisugi as Mikisugi-san (lit. "Mr. Mikisugi"), to his shock, when she places him in charge of the Naked Sol. Satsuki displays that she is still dead-set on accomplishing the mission at hand. For example, in Episode 23, she follows Ryūko's plan, distracting Ragyō while allowing Ryūko to reach the Life Fiber core unhindered. Later, in Episode 24, she tells the Elite Four to destroy the transmitter while she and Ryūko fight Ragyō.

In Episode 24, as Ryūko falls back to Earth, Satsuki screams at her to hang in there, and catches her with the help of essentially every other character, holding on to her as the force from Ryūko's descent propels them all backward into the school. Once the dust settles, she gives Ryūko a warm welcome home.

During the credits, Satsuki is shown joining Ryūko and Mako on their "date", showing that she is really a kind individual who has come to care greatly for her little sister. She also shows a somewhat shy side as she blushes when Mako and Ryūko take a picture of the three of them together.

Powers and Abilities

 * Natural Capabilities
 * Physical Prowess - Satsuki is accepted as the most powerful fighter of the Academy with almost superhuman physical strength, speed, endurance and reflexes. Her middle-school self was able to emit a fighting spirit capable of downing 500 men, and she was able to incapacitate Ira Gamagōri despite his superior size, age and with him wearing steel armor. Even when stark naked, and with her hands restrained, she still had enough skill and power to kill multiple COVERS using nothing more than her two altered toenails.
 * High Intelligence - She is also highly intelligent and manipulative as seen by her plan to take down her mother and the various people she deceived and manipulated in the process. Likewise she demonstrated a strong sense of patience and willpower, to endure the capture and torture at the hands of her mother, while slowly planning an escape route and having the forethought to alter two of her toenails using the same material as her sword Bakuzan.
 * False Toenails
 * Satsuki also has two toenails made of the same material as the Bakuzan, which she can use just as effectively.

Former Powers and Abilities
After her first clash with Ryūko, Satsuki donned the Kamui Junketsu and was able to force the blood-thirsty uniform to bow to her will. Her utter lack of shame at her appearance also allowed her to immediately attain Junketsu's Life Fiber Override and true form. Under Junketsu's power, Satsuki is granted incredible power, and even the smallest of attacks are capable of causing exceptional devastation. She is also capable of altering her Kamui's shape, as seen when she altered one of her shoulder guards into a drill to attack Ryūko. However, due to her inability to overcome the human race's resistance to the Life Fibers, she is unable to fully synchronize with her Junketsu, thus being shy of it's full power and capabilities, while exerting greater pressure and fatigue on her body.
 * Kamui Junketsu
 * Life Fiber Override

After Ryūko rips off Junketsu and being freed of Ragyō's mind control, Satsuki has Junketsu modified, such that it is infused with the blood of Ryūko and Mako, as well as the fibers of Senketsu, to tailor it to her needs. As a result, Junketsu now gains access to Senketsu's alternate forms while placing much less stress on her body.
 * Kamui Senketsu
 * Life Fiber Synchronize – After Ryūko is brainwashed by Ragyo and forced to don Junketsu, Satsuki wears Senketsu to combat Ryūko. She states that even though Senketsu may dislike her, only she and him can stop Ryūko. While transformed, Satsuki is shown to be able to use all of Senketsu's alternate forms such as Senketsu Senjin and Senketsu Shippu, although not at their full power.

Ryūko has stated that Satsuki and Senketsu are not truly synchronized, and Satsuki is merely commanding Senketsu to do as she says. Despite this, Senketsu acknowledges that Satsuki and its heart are one with the desire to bring Ryūko back to her senses. Senketsu is eventually shredded apart by Ryūko, but reforms itself in time to protect Mako.


 * Secret Sword Bakuzan Satsuki is a master swordsman who wields the Bakuzan, a black-bladed katana in a white sheath with an edge that is claimed to be keener than Ryūko's Scissor Blade. Its strength is so great that one slash is enough to damage a transformed Kamui. While durable enough to clash with Ryūko's Scissor Blade on their multiple battles, the Bakuzan was eventually broken when clashing against Ragyo's fist.
 * Bakuzan Gako and Bakuzan Kōryu
 * Swordsmaster - Bakuzan was a special sword capable of severing Life Fibers, that was noted by Satsuki to have a sharper edge than that of a Scissor blade. It was eventually broken in half in the battle against Ragyo. The shards are eventually reforged into Bakuzan Gako and Bakuzan Kōryu, a long blade and short blade respectively, which are given to Nonon Jakuzure and Ira Gamagōri respectively. Bakuzan Kōryu is then passed onto Uzu Sanageyama, as Gamagōri claims that he is more proficient with blades. Both blades are returned to her by Sanageyama and Jakuzure. Now holding two blades, their effect is the same as the twin Scissor Blades, being capable of damaging Life Fibers beyond their regenerative powers. Satsuki's skill with these blades is extensive and adaptable, as she has gone toe-to-toe against various other sword wielding opponents.

Trivia

 * Episode 1: Satsuki's "facts of this world" are heavily inspired by George Orwell's most famous novel, Nineteen Eighty-Four. In the novel, the Party's slogans—"War is Peace", "Freedom is Slavery", and "Ignorance is Strength"—were paradoxical statements that held hidden truths about the world in the novel. Satsuki's "facts of this world" speech, coupled with Ira's execution of the Goku Uniform thief, were intentionally chosen to introduce her as a ruthless dictator.