Senketsu

"Don't you touch her. If you do, I'll make you pay!"

- Senketsu to Tsumugu Kinagase, Episode 5.

Senketsu (鮮血) is a Kamui created by Isshin Matoi who's later revealed to be Sōichirō Kiryūin, and is the the deuteragonist of Kill la Kill. Appearing as a sentient sailor uniform, he was found by his creator's daughter, Ryūko Matoi, becoming her primary ally in her battle against Satsuki Kiryūin and later, Ragyō Kiryūin and COVERS.

Appearance
Senketsu appears to be a navy-blue and red sailor suit with the midriff shown and a lower-cut skirt. When Senketsu is on his own, the section between the shirt and skirt resembles a mouth, in that he is attached to his lower jaw at the back. When he is worn, however, the skirt is connected to the upper body by three suspenders. He speaks to Ryūko with a deep male voice and everyone refers to him with male pronouns, even though Kamui are technically agender entities.

Personality
In most circumstances, Senketsu is a composed and analytically individual, calmly observing and assessing situations as they occur. He maintains this level-headedness even in the heat of battle, thinking of attack strategies, giving Ryūko advice and warning her whenever she is about to run out of energy. He initially shows a manic and aggressive craving for Ryūko's blood, as he needs it to remain active, although this is satiated once she starts wearing him regularly.

Despite being an article of clothing, Senketsu is shown to have undeniably humanistic qualities, such as genuine and even fatherly love of Ryūko, crying when getting sentimental and feeling lonely whenever Ryūko is not wearing him, which is accentuated by the fact that only she can hear his voice.

Senketsu is horrified of being washed by hand, as it is quite painful for him. However, he is fond of being ironed, which he finds soothing.

Synopsis
Senketsu was created by Isshin Matoi as a nameless Kamui specifically for his daughter, Ryūko, with the purpose of fighting off the threat of the Life Fibers. Isshin imbued him with Ryūko's DNA; as such, only she can communicate with and properly wear him.

Some time after his creation, he was hidden by Isshin under a pile of clothes during Nui Harime's invasion into his laboratory. There he remained inactive until Ryūko fell into the room, inadvertently reawakening him when blood from a reopened wound dripped on him. Desperate not to fall asleep again, he forcefully put himself on Ryūko. Once he regained his composure, he told her he remembered little more than his powers and creator. Ryūko reasoned she could use his powers in her battle against the Student Council of Honnōji Academy, and named him "Senketsu" after the fresh blood that awakened him.

Ryūko effectively wears Senketsu in their first battle together against council member Takaharu Fukuroda. However, she overexerts herself and is advised by Senketsu to run away before she collapses from fatigue. The next day, Senketsu fails to awaken because Ryūko was unable to feed him, resulting in her defeat against Omiko Hakodate. To rectify this, Ryūko's homeroom teacher Aikurō Mikisugi gives her a Seki Tekkō, a glove that allows her to conveniently draw her blood to keep Senketsu fed and active.

During the battle against Satsuki and her Kamui, Junketsu, they were outmatched at first, but Ryūko was able to perform better with Senketsu when she finally became able to wear him in public without feeling embarrassed, achieving full Life Fiber Synchronization and unlocking his full potential. Together, they nearly match Satsuki and Junketsu's power.

During the battle against Nui, Ryūko's rage caused her blood temperature to elevate to the point that Senketsu was no longer able to control himself. This caused Ryūko's rage to overwhelm him, transforming them both into a berserk abomination. While she was eventually calmed and Senketsu returned to his normal state, the fear of the encounter left Ryūko hesitant in her next meeting with Nui, the result of which was Senketsu's destruction. His remains were then taken by Satsuki and given to Shirō Iori to be added onto uniforms of students deemed worthy of such power. Ryūko had however managed to hold onto a piece of him, which she put on a scarf for the time being.

Ryūko then sets out to the raid trip to retrieve the rest of Senketsu, in which she does successfully, aside the glove, which was being worn by Satsuki. After fixing Senketsu, the two confirm their friendship and how Senketsu will help achieve Ryūko's goals. After, Ryūko asks Senketsu to transform at the risk of her hand not being able to handle the life fiber flow. Ryūko successfully does so and retrieves the glove. Senketsu and Ryūko then learn of how Nudist Beach was formed and what Isshin Matoi had set to achieve.

During the school festival, Ryūko and Senketsu both comment on how powerful they have become, being able to overpower Nui Harime. Soon after, Ryūko learns of how she is perfectly merged with life fibers, and not human. After Satsuki blows the Academy up, Senketsu drags the unconscious Ryūko to Aikuro, and then watches over her while she is in a comatose-like state. Sukuyo Mankanshoku comforts Senketsu, knowing that he is worried for Ryūko.

Separation and Reunion
After Ryūko wakes up and destroys a number of COVERS in a fit of rage, Senketsu asks for her to put him on. She refuses, stating she isn't human, but a Life Fiber monstrosity, just like him, leaving him shocked. Ryūko expresses her distress to Senketsu and the others on discovering that she, not Senketsu, was the weapon made to battle Life Fibers. Mako Mankanshoku tries to make Ryūko put him on again, but she goes into another fit of rage by the sudden appearance of Nui and Ragyō, who in turn tells her to go to Honnōji to settle their scores. Senketsu tries to tell her not to go but she recklessly steals a motorbike and goes anyway. Senketsu ends up talking to himself trying to tell his allies that he wants to go to Honnōji to save Ryūko, though Mako manages to speak up for him. Although Mako cannot actually hear him, she hugs him before Mikisugi activates the S.S. Naked Sun, a Nudist Beach carrier ship fully funded by Takarada. They launch and depart after Ryūko.

After Ryūko lands on the Naked Sun and begins destroying everything in sight, Satsuki requests Senketsu's assistance in stopping her sister, even though Senketsu may dislike her. Senketsu agrees to this and Satsuki wears him into combat. Even with Senketsu's power and shifting into his Blade Flash and Gale forms (even using a combination of both dubbed "Blade Gale"), Satsuki fails to stop Ryūko and Junketsu. Ryūko manages to break Senketsu's blades and push Satsuki to her limits. When she is about to be executed by Ryūko's Decapitation Mode, the Elite Four intervene. Before Ira can use the Suction Device to separate Junketsu from Ryūko, Nui reveals that she had literally sewn her into Junketsu. In other words, attempting to separate the two could be fatal.

In desperation, Satsuki gave Senketsu to Mako and sent them to try and snap Ryūko out of her brainwashing. Senketsu protected Mako from Ryūko's attacks as they entered her mind, and blocked another strike from Ryūko in her mental world. The shock of almost murdering her closest friends snapped Ryūko out of her brainwashed state, forcibly expelling Senketsu and Mako from her mind before ripping Junketsu off of herself.

With Ryūko back to normal, Mako threw Senketsu in her direction so they could finally recombine. Nui attempted to attack the Kamui with the Scissor Blades, but Senketsu cleverly separated himself into two halves, dodging the attack and using Nui as a springboard to reach Ryūko and fuse with her. After Ryūko overwhelmed Nui and severed her arms with the reclaimed Scissor Blades, Senketsu absorbed the Life Fibers of Nui's arms when they were rendered inert by the power of the Scissor Blades. After Rei spirited Nui away in a helicopter, Ryūko attempted to pursue with Senketsu Shippu form. However, the Kamui chose not to respond, telling Ryūko that she had already lost too much blood to risk chasing Nui down.

Final Battle
After Ragyō donned Shinra-Kōketsu and absorbed Rei to activate its "Absolute Domination" ability, Senketsu was forcibly reverted to his normal form. Ryūko eventually removed him in order to fight Nui, having realized that she was immune to Ragyō's powers by virtue of being a human-Life Fiber hybrid. When Ryūko appeared to be losing against Ragyō, Senketsu cried out in concern, only for Satsuki to reassure him that Ryūko wouldn't be so easily defeated. The revelation that Satsuki could hear him made Senketsu realize that he was also a Life Fiber-human hybrid (due to containing some of Ryūko's DNA), allowing him to activate his Blade Gale form and drill through Ragyō, dislodging Rei in the process.

With Absolute Domination disabled, Senketsu fused with Ryūko and joined Satsuki in attacking Ragyō with the Scissor Blades. They dealt a severe blow to the REVOCS director, but Ragyō recovered by fusing with Nui and the Original Life Fiber. With their foe blasting off into space to activate Life Fibers across the Earth, Ryūko had Senketsu absorb the Life Fibers of everyone's Goku Uniforms (including Junketsu) to reach the peak of his power, becoming Senketsu-Kisaragi (Fashion Week) and allowing them to pursue Ragyō.

Facing off with the elder Kiryūin in space, Senketsu and Ryūko unleashed everything they had against Ragyō, but Shinra-Kōketsu proved impervious to their blows. However, this proved to be part of their real plan; by taking Ragyō's attacks in his empowered state, Senketsu gradually increased his ability to absorb Life Fibers. When his powers reached their peak (after Shinra-Kōketsu impaled Ryūko through the stomach), Senketsu was able to absorb the ultimate Kamui, gaining its Absolute Domination ability. Ryūko then used her new power and the REVOCS satellite to command all Life Fibers on Earth to abandon humanity, stating that "humans are humans and clothing are clothing".

With the Earth freed from the Life Fibers and Ragyō dead by her own hand, Ryūko and Senketsu prepared to return to their friends and family. However, Senketsu discovered that Shinra-Kōketsu's power was even greater than he had anticipated; the strain of absorbing it was causing him to disintegrate. Deciding to make his last moments count, the Kamui immediately made a beeline for Earth, removing himself from Ryūko's body to shield her from the heat of re-entry.

As he burst into flames, Senketsu told Ryūko that he had enjoyed their time together, but explained that she had "outgrown her sailor uniform". His final words were to encourage the girl to wear "clothing much cuter than I could ever be" in the newly-freed world she was returning to. After a grief-stricken Ryūko agreed to his last request, angrily declaring that she would wear clothes that would make him "green with envy", Senketsu finally broke apart into ashes and a few stray Life Fibers that disappeared into the air.

"First Graduation Ceremony"
Senketsu appears in the episode as a spirit in Ryūko heart. Helping her during her near defeat against the Honnōji Academy Final Defense Apparatus by sending in the Rending Scissors, being represented by a red star. He also briefly appearing as a spirit, during Ryūko charge against the Final Defense Apparatus. At the very end of the episode, the shining red star appears, showing that Senketsu will be always in Ryūko's heart.

Powers and Abilities
As a Kamui, when fed with blood, Senketsu has the ability to change into very revealing armor that grants Ryūko immense power. Initially the extent of power was limited and the blood drain was a constant problem due to Ryūko's embarrassment at her appearance, but after she comes to terms with it, they were able to use the Life Fiber Synchronization to achieve the full power of a Kamui while minimizing the blood drain. In addition, although very skimpy in appearance, Kamui are implied to "become the wearer's skin". Senketsu's "activated" when Ryūko uses the Seki-Tekko to draw blood. A needle draws out a set amount of blood and allows her to use Senketsu in his battle form.

A few times, Senketsu's power has been diminished or is limited. It's seen that Senketsu's armor changes in these limited forms: in the first few episodes, the armor's skirt had no spikes, the eye crest were smaller and more compressed and Ryūko's hair wasn't as spiky. While being worn by Maiko Ogure, the crest was upside down, the skirt was stuck facing upwards and her arms were exposed.

Senketsu is the only Life Fiber uniform (COVERS not included) which can move and act independently of a wearer. This is likely due to his partially human genetics. He lacks proper legs and thus can only move by awkwardly hopping when on his own, but displays an impressive strength and stamina, and once dragged an unconscious Ryūko over a long distance. His "mouth" can bite enemies, as displayed in Ryūko's first battle against Ira Gamagōri. In the final battle against Ragyō, he is actually able to transform himself into a bladed drill-like configuration and attack Ragyō on his own, despite not being worn at the time.

His status as a Life Fiber article with human DNA infusion also grants him the ability to, when not worn, resist Shinra-Kōketsu's Absolute Domination, which paralyzes regular Life Fibers. This resistance is shared by humans infused with Life Fibers, such as Ryūko herself.

Embarrassment: Ryūko's unwillingness to fully wear Senketsu and become one became a huge issue with the first few episodes. Unable to draw out his power, Senketsu was forced to keep drinking her blood to remain active. After understanding how to master Senketsu, less blood was needed to stay active and the armor's full power was unleashed.

Wearer: Senketsu is a Life Fiber sailor uniform with Ryūko's DNA. This is likely due to Isshin believing his daughter's status as a human with Life Fibers would rival his ex-wife and allowed Senketsu to stay somewhat safe from others. Only Satsuki has been able to use Senketsu successfully, although they weren't in total harmony. This is likely due to Satsuki being Ryūko's sister, therefore sharing similar blood.

Although Maiko Ogure was once able to activate Senketsu (something he himself attributed to her total lack of shame), she was unable to move while wearing him. This implies Senketsu can gain some measure of control over a wearer's body if he wishes to.

Beserker Mode: When Ryūko's anger at Nui made her blood boiling hot, Senketsu became a bloodthirsty monster. It also caused his armor form to change into a chaotic, blood leaking version of itself, mutating it's wearer into a green-skinned, jagged toothed creature.

Absorption ability: In addition to the standard abilities of Life Fiber clothing, Senketsu has the ability to absorb the Life Fibers of defeated Goku Uniforms and Kamui, increasing his power. In addition, Senketsu possesses more than one Banshi, which may be a consequence of his absorption ability. This absorbing power was the downfall of Ragyō, since Senketsu absorbed her Absolute Domination power to use it himself.

Later, after witnessing Ira Gamagōri's Goku Uniform and its ability to undergo a secondary transformation, Senketsu was able to apply the idea to himself and gained the ability to change his configuration in the middle of battle to gain a better advantage. Known configurations are shown below.

Senketsu Senjin (鮮血閃刃)
 * In this form, Senketsu protrudes blades from all over its body. Senjin also has retractable claws. These claws can also be used during Senketsu's normal-mode and was also upgraded to a blade made of Ryūko's blood once.

Senketsu Shippu (鮮血疾風)
 * Senketsu's flying form. The bottom part of the uniform becomes a jet propulsion, and the crest (Senketsu's "eyes") becomes wings.

Senketsu Mubyōshi (鮮血無拍子)
 * This was used during the fight against Nonon Jakuzure to negate her sound wave attack and use it against her.

Senjin Shippu (鮮血刃疾風)
 * Combines the blades of Senketsu Senjin and the jet propulsion of Senketsu Shippu to create a hybrid form with boosted offensive capabilities.

Senketsu Kisaragi (鮮血更衣)
 * Senketsu's ultimate form. Combines the powers of Junketsu and the Goku Uniforms to create the strongest form with boosted stats.

Ryūko Matoi
Ryūko is Senketsu's closest friend and partner/wearer in combat. Originally she considered him to be a simple tool to use and find her father's killer with, although this eventually develops into a strong relationship. In battle, Senketsu's tactical thinking usually counteracts Ryūko's recklessness by trying to calm her down when she is overwhelmed, offering attack strategies and warning her whenever she is low on energy.

It is shown that Senketsu does have jurisdiction over who wears him and how, such as in Episode 3 when he transformed back into a sailor uniform by himself to keep Ryūko from fainting, and in Episode 4 when he didn't allow Maiko to move once she forcibly put him on.

Episode 5 shows a big development in Ryūko and Senketsu's bond. Knowing that it was he who Tsumugu Kinagase was after when he attacked Ryūko, he tells her not to wear him so that Tsumugu wouldn't hunt her down, but Ryūko is dismissive of his comments and states that he is just her clothing and should let himself be worn. Once Senketsu reaches his limit due to Tsumugu's jamming rounds, Senketsu gives himself up to protect Ryūko, telling her to run and save herself. Mako interferes and gives a speech about how Senketsu is Ryūko's friend, and returns Senketsu to Ryūko before leaving. Ryūko protectively clutches Senketsu and refuses to give him up again, saying that the only time Tsumugu would be able to get him back was if he killed her. Tsumugu hesitates, and Senketsu somehow communicates with him, saying that if he harms her, he'll make him pay. The end of the episode has Ryūko saying that Senketsu isn't just her clothing, but her friend, and he responds that he is indeed.

In Episode 18, Ryūko and Senketsu achieve total synchronization, with Ryūko being able to move at lightning speed in her battle against Ragyō.

Though, in Episode 19, Mako is taken by a COVERS suit and Satsuki blows up the stadium the battle was taking place. Senketsu managed to stay awake and tried to protect an unconscious Ryūko against COVERS, but they were actually found by Mikisugi and taken to a Nudist Beach base. Ryūko apparently remained in a coma for the rest of the month while Senketsu waited for her to wake up. When she wakes up and defeats all of the COVERS surrounding the base in a single strike of the Scissor Blade, Senketsu becomes overjoyed. But, in a fit of rage, Ryūko says that she now hates the mere sight of him and will never put him on again, much to Senketsu's shock.

However, despite this, Ryūko rekindles her bond with Senketsu in Episode 22 after she rips Junketsu off in a fit of rage after coming back to her senses.

At the end of episode 24, Senketsu sacrifices himself in order for Ryūko to return home safely, causing Ryūko immense grief before she goes unconscious. A while later, when she, Mako, and Satsuki are on their date, she spotted a young girl wearing a sailors uniform that have a similar color scheme to Senketsu. She looks up to the sky and feels the section where Senketsu's eye was present.

In episode 25, Ryūko is reminded about Senketsu from Mikisugi because she's now wearing "new clothing". Mako soon jumped in, telling that Senketsu lives inside her. During Ryūko's fight against the Honnōji Academy Final Defense Apparatus, the spirit of Senketsu, represented by a red star, sends the Rending Scissor to Earth during her near defeat. As it caught up to Ryūko during her fall, she grabbed on to it and use it to slow her descend and then proceed to run up a wall. During her battle against the Final Defense Apparatus, she sees the spirit of Senketsu before detached the Scissor Blades and then increased both scissors to a monstrous size where, along with the remains of the S.S. Naked Sun, destroyed the Final Defense Apparatus. At the very end of the episode, the shining red star appears, showing that Senketsu will be always in Ryūko's heart.

Satsuki Kiryūin
When Ryūko falls victim to Ragyō's brainwashing and is worn by Junketsu, Satsuki wears Senketsu in an attempt to stop them. She asks for Senketsu to lend her his power, despite any feelings of hatred he may have for her. During the battle, Satsuki is forced to tell Senketsu what to become in order to counter Junketsu; he notes that Satsuki's choice of forms are "interesting". After this, Senketsu shows some respect for Satsuki for risking her life for Ryūko, referring to her by her given name. Later, in the last episode, Satsuki reassures Senketsu, saying she shares his worries about Ryūko, but reminds him of the girl's tenacity. By hearing and responding to him, Satsuki helps Senketsu realize his evolution into something that, like Ryūko, is "neither human nor clothing".

Memorable quotes
"Don't leave! Put me on! Put me on! Wear me and feed me blood! I don't wanna go back to sleep! You're wasting time! Don't be scared! Put me on! Put me on!"

- Senketsu clings to Ryūko after waking up from his slumber, unable to contain himself

"Am I... feeding off Ryūko?!"

- Senketsu panics as he learns the truth about the Life Fibers and their parasitic behavior