Episode 25

"Goodbye Once Again" is a bonus episode that is included in the 9th DVD/BluRay volume of Kill la Kill, which was released on September 3, 2014. On June 7, 2014, Shigeto Koyama and Hiromi Wakabayashi confirmed during a Q/A session at AnimeNEXT 2014 that the theme of the OVA will be "graduation".

Plot
Two weeks after Ragyō's defeat, Honnōji Academy has served its purpose and is to be decommissioned within a month. Ryūko is at its ruins with Mako and the Elite Four watching over a friendly match between Satsuki and Sanageyama. He strikes repeatedly, but Satsuki vanishes and breaks his sword. He then is questioned by the other Elites and says Satsuki's previous resolve is gone, and as such he couldn't bring himself to strike her. Below at the town, the citizens are packing up to leave, including the Mankanshoku Family. Mataro says goodbye to his gang, advising them to enroll in elementary once they move, and Sukuyo gives them "goodbye croquettes". His father reminds him they're moving as well, so he then goes to help packing by picking up their house and putting it into their truck. At the remains of Honnōji Academy, the "First Graduation Ceremony" is about to begin.

Ryūko, sitting by herself against a wall, intercepts Mako as she comes flying right at her in typical manner. She tells Ryūko that they will both be transferring to "Rinne High School" in Kanagawa. Mikisugi appears near the duo in his teacher garb, saying that he was invited to the ceremony as the History teacher. He then asks Ryūko how is she dealing with regular clothes since he was the one to arrange her and Senketsu to meet; reminding her that there are still Life Fibers in her. Mako jumps in and reminds them that Senketsu is alive within Ryūko, and she will always be wearing him. Aikurō expresses relief before revealing the futures of the Elite Four members: Gamagōri will be working at a relative's iron works, Nonon will inherit the Jakuzure Corporations, Hōka will pick an IT graduation, Iori will continue his study of Life Fibers as they move into college, and Uzu will work at home with his family while he continues kendo. He then says Satsuki is the only one left and Ryūko reply's that "she's trying to find a way to put down her sword. After spending her whole life sharpening its edge."

Atop of the ruined tower, Satsuki is enjoying a cup of Soroi's tea. Soroi tells Satsuki that the ceremony is about to begin in which she tells him to go make tea for all the students to drink and thanking him for all he have's done. As Soroi leaves, Satsuki was soon interrupted by a clone of herself and states that she knew they would come.

Ira Gamagōri demands the students' attention, declaring that the ceremony will begin with a speech from Satsuki. On cue, light shines from the tower above but instead in red and black glow heralds the appearance of the false Satsuki, declaring the graduation "nonsense". Uzu is question on what Satsuki was saying while Ryūko wonders if she was switching sides in which Nonon commented that she wouldn't do such a thing. Hōka points out to Iori about her outfit in which he states that she's wearing Junketsu. Satsuki is suddenly joined by doubles of the Elite Four, all wearing their first Goku Uniforms iteration. The false Elite Four echoes their master's words before going on the attack, transforming their uniforms into dark versions of the Elite Four's original Three-Star Regalia.

The students scatter within the sudden assault, with False Inumuta revealing that he has hacked his counterpart's computer to prevent him from analyzing the situation. Ryūko attempts to fight back, only to be met by the False Satsuki and her dark version of Junketsu Override. Luckily, Tsumugu arrives with weapons for everyone including a set of Tailor Dagger's for Ryūko, and customized DTRs for the Elite Four. Although the Elite Four balk at the idea of using the mecha, they realize that they have no other choice at the moment - especially since Tsumugu is quickly defeated by False Gamagoori - and so they don their Nudist Beach uniforms and engage their doubles in the DTRs. Meanwhile, Ryuko demands to know where the real Satsuki is, only for False Satsuki to declare that she is the real Satsuki.

In truth, Satsuki is trapped in the academy's engine room, tied to a strange machine with Life Fibers and trying to reason with her captor: Rei Hōōmaru. Rei demands to know why the heroes never bothered to kill her like they did Ragyō and Nui. Satsuki claims that her war with the Life Fibers taught her that everyone deserves a second chance, leading Rei to deduce that her quarry allowed herself to be captured. Satsuki says it's a way of putting away her sword and explains that she is willing to die if it satisfies Rei's grudge. The former REVOCS executive angrily retorts that one death will not compensate for the loss of her superior, stating the world is steeped in injustice, where the strong dominate the weak; believing that's the nature of humanity and its idiocy.

A flashback occurs to 20 years prior to the main series, revealing that Rei was originally an African child whose hometown was caught up in a civil war. Ragyō, who was searching for humans with high Life Fiber compatibility, saved the child by dismembering the soldiers. Learning that the girl had immense potential, Ragyō took her in, naming her "Rei Hōōmaru" and giving her a pair of green aviator sunglasses.

Back to the present, Rei states "this place" before giving a malicious chuckle. Outside, the Elite Four have abandoned their DTRs to fight their doubles directly, due to being unfamiliar with the controls of their mechs. Aikuro protests, even when Inumuta remotely controls the DTRs to distract False Sanageyama, declaring that they have lost their beauty - from the wreckage of his motorcycle, Tsumugu is appalled to learn that his friend actually liked the DTR's design.

Suddenly, the entire academy shakes and rises up, transforming into a massive robot vaguely resembling Junketsu. Shiro Iori identifies this as their "Last-Stitch Weapon" against the original Life Fiber, never put to use due to Ragyo's takeover of the academy. Within the mecha, Satsuki realizes that she is powering its core, but Rei points out that she has a backup battery in case she thinks of committing suicide - Mako, apparently captured after the clones set up a cheese trap to distract her. Noticing Satsuki's glare, Rei gleefully explains that she created her clones from the One-Star students' memories of her original reign of terror over the academy, declaring that Satsuki's injustice will now bring doom upon her friends.

Down below, the Elite Four are increasingly pressed by their dark doubles, who appear to match them in strength. Confident of victory, Rei prepares to strike, but Mako somehow hijacks the controls long enough to make the robot mirror her poses as she gives a speech to her friends, declaring that they've all become stronger through their trials together. Inspired by the No-Star's words, the Elite Four suddenly turn the tables on their opponents: Nonon uses a sound-negation field to explosively reflect her double's attacks back to their source; Gamagoori punches into his clone and severs its Banshi; Inumuta sneaks behind his doppelganger and strikes its uniform's weak spot (a power button on the back of the neck) before smashing it with a keyboard; and Sanageyama deflects his imitator's shinai barrage before slicing it in half. Finally, Ryuko locks blades with False Satsuki and flips over her head, ripping out her Life Fibers in the process.

Angrier than ever at the loss of her creations, Rei unleashes the full power of the academy mecha, causing its arms to separate into multiple tentacles as it pulls itself free of the island. Ryuko is struck by debris and falls into the new chasm below, but resolves to keep fighting and protecting her friends. As she thinks of Senketsu, the Kamui's voice echoes from above, telling her to "use this"; moments later, the Rending Scissors drop from the sky, allowing Ryuko to begin rushing up to the robot again. Everyone looks on in awe as Ryuko dodges bullets, debris, and giant metal arms, declaring that no one can live in the past forever.

The enraged Rei directs her mecha to pick up the S.S. Naked Sun to use as a weapon against Ryuko, but the Life Fiber hybrid responds by transforming her Scissor Blades into gigantic cleavers, dwarfing even the academy robot itself. Repeating her statement that today is when they all finally "graduate" from the trials behind them and the shadow of Ragyo, Ryuko delivers a massive double cut that tears the robot in half.

(More to come)

Characters

 * Ryūko Matoi
 * Satsuki Kiryūin
 * Mako Mankanshoku
 * Senketsu
 * Ragyō Kiryūin
 * Ira Gamagōri
 * Hōka Inumuta
 * Uzu Sanageyama
 * Nonon Jakuzure
 * Shirō Iori
 * Rei Hōōmaru
 * Aikurō Mikisugi
 * Tsumugu Kinagase
 * Mankanshoku Family

Trivia

 * The neon green color palettes used for most of the ghosts and weapons are based on the original concept color scheme for Senketsu.