Satsuki Kiryuin is the powerful student council president of Honnouji Academy and the wearer of the kamui, Junketsu.
Satsuki has been driven in a plot of revenge since she was five years-old, and her father, Soichiro Kiryuin, revealed the truth to her about her mother, Ragyo Kiryuin. They had experimented on Satsuki on trying to bond Life Fibers to the human nervous system and failed, then turned to Satsuki's baby sister soon after her birth. The death of this child is what turned Soichiro to betray Ragyo, and he was also killed. Has grew up, Satsuki pretended to follow her mother's commands as a loyal agent of COVERS. All while plotting her vengeance for the deaths of her father and unnamed baby sister.
What she ended up creating was the Honnouji Academy, where she was student council president; and the Goku Uniforms, which supplied her loyalists enhanced powers. The Elite Four of her student council was Nonon Jakuzure, Ira Gamagoori, Houka Inumuta, and Uzu Sanageyama. Across Japan, her influences grew and it swept across the nation with each region she conquered. Only the Kansai region remained in the way of complete national domination of the school system.
Satsuki Kiryuin is a main character of the Kill la Kill anime series that was produced by Trigger. It's directed by Hiroyuki Imaishi and written by Kazuki Nakashima. The character design was done by Sushio. The series first began in October 3, 2010.
Her first anime appearance was in Kill la Kill - Episode 1 "If Only I Had Thorns Like A Thistle…". Her character in the Japanese series was voiced by Ryoka Yuzuki. while Aniplex America has Carrie Keranen voicing her in the English version.
Satsuki's rule over Honnouji Academy stood unchallenged from any true opposition as she spread her will and the will of the Kiryuin Clan throughout the nation. That was until a drifter name Ryuko Matoi appeared wielding a Scissor Blade and looking to challenge her and learn who killed her father. She appeared to be no real threat until she returned from her initial defeat wearing a kamui she called Senketsu. Time and again, Ryuko defeated her Student Council members to get to Satsuki.
After finally having had enough and angered someone would beat her to the punch of donning a kamui, Satsuki stormed into her family's home to claim her Junketsu. In-spite of her mother's will, Satsuki unsealed Junketsu and gained its power. Satsuki's first test of this new power was put against Ryuko the very next day. She grossly outclassed Ryuko up until she had finally synchronized with Senketsu. From that point on, the battle was far more evenly matched.
The battle ended in a draw, but Satsuki made a deal with Ryuko. If she could defeat all the members of the Honnouji Student Council, they would have another rematch. Only then would Satsuki tell her what she so desperately wanted to know.
Satsuki sat back and watched as many of the student council members attempted to take down Ryuko to increases their own power. Sanageyama was defeated, but Satsuki allowed him to return once he showed his resolve by having his own eyes sewn shut. Satsuki then tested the friendship between Ryuko and Mako Mankanshoku by giving her a two-star uniform. Not long after, Satsuki initiated the First Annual Naturals Election. This weeded out the "undesirables", then pitted Ryuko against her Elite Four in a tournament. Gamagori, Inumuta, and Jakuzure all lost their fights, but the rematch between Ryuko and Sanageyama was interrupted by the sudden appearance of Nui Harime, who revealed herself to be Isshin Matoi's killer.
Satsuki stepped into the battle between Ryuko and Nui as Ryuko lost control of herself and transformed into a mindless monster. Satsuki was ready to strike Ryuko down after her attempts to bring her to her senses failed, but she instead ended up blocked Nui from stopping Mako from saving Ryuko. Several days later, Ryuko came to see Satsuki as Honnouji Academy was being rebuilt in order to find Nui. However, Satsuki told her to direct her anger to herself, since she was the one who sent Nui to retrieve the Rending Scissors and the Kamui. However, Satsuki thanks Ryuko, because of her battles she was able to discover the weakness of the Goku Uniforms and improve them.
After confirming her plans for the Kansai School Raid Trip and discussing Nui's appearance with her mother, Ragyo Kiryuin, Satsuki returned just in time to save Ryuko from being murdered by Nui. While Ryuko was unconscious, Satsuki gathered the shreds of the destroyed Senketsu, covered Ryuko where she lay, and took the pieces of the Kamui to Shiro Iori to have them incorporated into the Goku Uniforms of suitable hosts.
The assault on Kansai went off with few problems. Osaka fell last, and Ryuko appeared to reclaim the Seki Tekko that Satsuki kept for herself. Upon wrenching the last piece from her to reform Senketsu, Ryuko and Satsuki engaged in a pitched battle that destroyed much of the city. The battle ended in a draw after Ryuko used a sneak attack to blind Satsuki with blood and steal Bakuzan. Satsuki stood down, but Nonon had already found and destroyed the Nudist Beach hidden base before they started to head back to Honnouji Academy. However, Satsuki was redirected to report immediately to her mother, after Nui took over her chopper while disguised as the pilot.
It was under the Kiryuin Manor that Ragyo revealed the Primordial Life Fiber, the source of all Life Fibers; and she ordered Satsuki to begin the preparations of the Cultural & Sports Grand Festival. Satsuki followed all her mother's required preparations, but the moment Ragyo turned her back while distracted by Ryuko's arrival, Satsuki ran her mother through the back with her sword and openly declared her revolt. Ryuko reluctantly joined Satsuki to fight her mother, but Ragyo turned the tables on Satsuki after she regenerated from the beheading. After destroying Bakuzan, Ragyo then stole Junketsu from her and tossed her aside. When her mother attacked Ryuko, pulling out her heart laced with Life Fibers, she revealed that her rival was also the baby sister that they both had thought to be dead. With Junketsu gone, Satsuki resorted to blowing up the stadium, but it failed to eliminate Ragyo.
Satsuki survived the blast and Ragyo kept her captive for over a month under the ruins of Honnouji Academy. Only coming to see her to humiliate her daughter and fuel her rage. All in the name of Ragyo's next plan, but Satsuki never gave in. While hanging from her cell, she sharpened the false toenail made of the same material as Bakuzan into a claw. She cut her chain as her Elite Four invaded the school, along with Nudist Beach. As she escaped to the Naked Sol, they were attacked by a brainwashed Ryuko in Junketsu. Without the power to stop her, Satsuki turned to Senketsu for help and the Bakuzan-Gako & Bakuzan-Kouryu.
Satsuki's training with the katana is unknown, but it's likely from traditional training. Her proficiency with the sword is nearly unmatched. Even from a young age, she was able to swing her katana with incredible force, even while it was sheathed. Later, she is seen to be even slightly more powerful than Ryuko with her activated kamui, After obtaining her own kamui, this only served to increase the power of her swordsmanship skill.
The Bakuzan is Satsuki's cherished sword. It's unknown where she gained this katana, but she is almost never seen without it. Her power with this sword was even greater that Ryuko's with her kamui. The materials of the blade are both strong and sharp enough to pierce any kamui. It was shattered while fighting her mother.
Junketsu is a kamui, a type of school uniform made of 100% Life Fibers, that Satsuki Kiryuin wears. He was created by the Kiryuin Organization specifically for her when she was a child. Her father called it her "wedding dress". However, he was eventually sealed away and she was forbidden to use it by her mother. This still didn't stop her from claiming it after she was challenged by Ryuko in Senketsu.
Though it normally appears to be white school uniform, it can transform into an incredibly powerful suit of armor that boosts her strength and speed. This ability is called Life Fiber Override - Kamui Junketsu (「人衣圧倒」神衣・純潔, "Jin'iattō" Kamui Junketsu) The cost of this power is that he needs to draw out Satsuki's blood. Using Override Mode is physically taxing on Satsuki's body if used for prolonged periods.
Kamui have been shown to be capable of various secondary transformation states. While Satsuki has shown her ability to manipulate Junketsu's shape in battle as grappler and spear, she has yet to reveal any evolution in Junketsu's abilities.