Senketsu

"Don't you dare lay a finger on Ryūko. If you do, I'll make you pay!"

- Senketsu to Tsumugu Kinagase, Episode 5.

Senketsu (鮮血) is a Kamui created by Isshin Matoi and the deuteragonist of Kill la Kill. Appearing as a living sailor uniform, he was found by Isshin'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 above the skirt resembles a mouth, in that he is attached to his lower jaw in the back. When he is worn, however, the skirt and the rest of him are completely separate exempting some suspenders. He speaks to Ryūko with a deep male voice, and everyone refers to him with male pronouns, even though Kamui are technically sexless 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.

Synopsis
Senketsu was created by Isshin Matoi as a nameless Kamui specifically for his daughter, Ryūko Matoi, 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 her 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 Kiryūin 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 Harime, 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 Senektsu, the two confirm their friendship and how Senketsu with 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. 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 a human, but a Life Fibers monster, just like him, leaving him shocked.

Later on, Ryūko expresses her distress to Senketsu and the others on discovering that she was in fact the weapon made to battle Life Fibers, and not Senketsu. Mako tries to make Ryūko put him on again, but she gets another fit of rage by the sudden appearance of Nui Harime and Ragyō Kiryūin, who in turn tells her to go to Honnōji to settle their scores. Senketsu tries to tell her not to go. She 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 and they hug 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, who 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 decide to intervene, only for Nui to interrupt Ira's attempt to use a Suction Device on Ryūko and reveal that she had literally sewn her into Junketsu - to separate the two would 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, but the Kamui chose not to respond, telling Ryūko that she had lost too much blood to risk chasing Nui down.

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".

Most uniquely to the Kamui, Senketsu has the ability to absorb the Life Fibers of defeated Goku Uniforms, making him grow stronger. In addition, Senketsu possesses more than one Banshi.

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 "eyes") becomes wings.

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. It has been used by Satsuki (and Ryūko, as seen in Episode 23).

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. This form is only used in Episode 24.

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 Ogure 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 skim to Senketsu. She looks up to the sky and feels the section where Senketsu's eye was present.

Memorable quotes
"Don't go! Put me on! And feed me blood! I do not wish to go back to sleep! You'll have time to be surprised after you 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