Junketsu

Junketsu (純潔)is a Kamui made by the Kiriyūin family. It was sealed away by Satsuki Kiryūin's mother because of its uncontrollable power. It is eventually donned by Satsuki in order to combat Ryūko Matoi and her own Kamui, Senketsu.

Personality
Little is known about Junketsu's personality as it never speaks. However, similar to Senketsu, it has a strong craving for blood and violently latches itself onto Satsuki Kiryūin after she feeds it hers.

In episode 6 it is shown to be under heavy restraint when not in use by Satsuki, this combined with Satsuki's technique "life fiber override" imply Junketsu's personality is more feral and demonic. Most likely in contrast to Senketsu's more caring and calm personality.

Junketsu appears to require more blood than Senketsu. This is evident by the transformation sequence of both Kamui, Junketsu has 3 needles peircing Satsuki's skin, while Senketsu only has 1.

History
Junketsu was created by the Kiryūin family to be worn by their young daughter Satsuki Kiryūin when she came of age; Satsuki's father called Junketsu her "wedding dress". Some time afterwards, Junketsu was sealed away in Kiryūin Manor by Satsuki's mother. Under her orders, Junketsu was kept under tight guard from everyone, even Satsuki herself.

Synopsis
Faced with Ryūko Matoi and her own Kamui Senketsu, Satsuki goes to Kiryūin Manor to retrieve Junketsu against her mother's wishes. Awakened by Satsuki's blood, Junketsu becomes crazed and clings to her body, craving more. Through sheer willpower, Satsuki keeps Junketsu's incredible power under control. She wears Junketsu in her next confrontation with Ryūko, dwarfing her and Senketsu's combined strength as Ryūko had yet to tap into Senketsu's full power out of embarrassment of the Kamui's "exhibitionist" appearance. Even after Ryūko manages to overcome this, Junketsu's strength still beats out Senketsu's. Amused by Ryūko's determination, Satsuki challenges her to defeat all the students in her school to prove herself worthy of facing her and Junketsu's power again.