Shinra-Kōketsu

"Satsuki's gonna get eaten by it. By my masterpiece."

- Nui Harime about Shinra-Kōketsu; Episode 19

Shinra-Kōketsu, sometimes translated as Omnisilk Kōketsu, is a massive garment produced by Nui Harime with the aid of mentally refitted Sewing Club members. Ragyō Kiryūin refers to it as "the ultimate Kamui". Ragyō eventually dons it to combat against Ryūko Matoi and Satsuki Kiryūin and their respective Kamui, Senketsu and Junketsu.

Appearance
Unlike Senketsu and Junketsu, which were both designed after sailor uniforms, Shinra-Kōketsu is designed after a traditional Japanese wedding dress, featuring large, billowing sleeves and a hood. It is huge compared to the other Kamuis; unlike Senketsu and Junketsu, the dress itself does not have any eye-like features, but instead extends several floating eye-like 'wings' when activated.

During the battle in space, Ragyō also briefly changes Shinra-Kōketsu from its wedding dress form to a form resembling a sleeveless gown, although this appears to be a spontaneous transformation rather than a named form like those exhibited by the other Kamuis.

History
Shinra-Kōketsu was designed by Nui and made with the assistance of Honnōji Academy's brainwashed Sewing Club. Following Ragyō's victory over Satsuki at the Great Culture and Sport Festival, she had Nui begin working on Shinra-Kōketsu as the final stage of her plan to dominate the world with Life Fibers.

In Episode 23, Shinra-Kōketsu was finally completed, allowing Ragyō to put it on and absorb Rei Hōōmaru. In the following episode, Ragyō used its power to immobilize the Goku Uniforms, leaving them helpless to stop her from activating Life Fibers across the planet. Ragyō then used her new outfit to revive the Original Life Fiber, having it consume her enemies to become even stronger.

However, Senketsu manages to resist the Absolute Domination (being neither human nor Life Fiber) and pushes Rei out of Shinra-Kōketsu, disabling its immobilization field. With that threat negated, Satsuki and Ryūko use the Scissor Blades to slash Ragyō into quarters while their allies destroy the satellite transmitter needed to activate the Life Fibers.

Unfortunately, under Ragyō's orders, Nui cuts off her own head and merges with the Original Life Fiber, which fuses with Shinra-Kōketsu. Healed of her wounds and manifesting enormous rockets on her skirt, Ragyō flies into outer space and activates the satellite directly, causing every human in the world to become Life Fiber Cocoons.

However, with the help of everyone, who sacrificed their Goku Uniforms (including Junketsu), Senketsu transforms into Senketsu Kisaragi, which allows Ryūko to fly outer space as well. However, the Scissor Blades have no use on Shinra-Kōketsu due to them being made out of hardened Life Fibers, so Ryūko absorbs Shinra-Kōketsu's Absolute Domination ability and used the satellite to explain that humans and clothing are different, thus turning the world back to normal, with Shinra-Kōketsu being destroyed.

Trivia

 * The term 纐纈 (Kōketsu) refers to a technique of tie-dying commonly used in the Nara era of Japanese history.