OVA: Goodbye Once Again
Otherwise known as the 25th and final episode. Uzu says that Satsuki's resolve has vanished, and it's like she's invisible; as such, he was unable to go all out against her.
Mako comments that Satsuki didn't shine (or snap her heal), further cementing that Satsuki's ability to shine is canon.
Despite almost all of the Life Fibers in the world being gone, Ryuko still has Life Fibers inside her.
Hououmaru Rei activates the Final Defence Apparatus, which turns Honnouji Academy into a robot, which was designed to combat the Primordial Life Fiber.
Hououmaru takes over Honnouji Academy using the left-over Life Fibers from REVOCS, though with the Primordial Life Fiber gone, the planet can't be made into a Cocoon Sphere.
Satsuki is described as being a first rate food source for the Life Fibers (and killing Satsuki would cause the Final Defence Mechanism to stop working).
Satsuki is used as a power source for the Final Defence Apparatus, and Mako is used as a back up source.
The Life Fiber clones are literally the past versions of Satsuki and the Elite Four, taken from the memories and fears of No-Stars and made physical with Life Fibers (this may or may not also tie into If, and some of the drama CD things I've been looking into).
Hououmaru says that the Final Defence Apparatus can destroy the world (which makes sense, given it was designed to battle the Primordial Life Fiber).
A young Ragyo regenerates from being shot and cuts several soldiers into pieces.
Satsuki and Mako have strong sources of bio-energy.
Nudist Beach created multiple custom DTRs for the Student Council for the final battle against Ragyo, but these were never used due to the Student Councils overblown resistance.
These DTR can be remotely piloted.
Nonon creates a sound negation barrier and blocks the attacks of her Life Fiber clone, before expanding the barrier to destroy her clone.
Gamagoori shatters the ground and defeats his Life Fiber clone.
The Final Defense Apparatus splits Honnouji Academy in two.
Ryuko calls to Senketsu for help, and Senketsu's spirit sends down the Scissorblades from space.
Inumuta's devices detects the Scissorblades entering the atmosphere at high speed.
Ryuko sees the spirit of Senketsu.
Ryuko's Graduation Ceremony, in which she cuts the Ultimate Defence Apparatus (and the Naked Dagger, being the S.S. Naked Suns weaponized form) in two.
Ryuko absorbs Life Fibers into her own being (which is why her hair is streaked red).
Senketsu shines in the sky.
Otherwise known as the 25th and final episode. Uzu says that Satsuki's resolve has vanished, and it's like she's invisible; as such, he was unable to go all out against her.
Satsuki and Mako have strong sources of bio-energy.
Gamagoori shatters the ground and defeats his Life Fiber clone.
The Final Defense Apparatus splits Honnouji Academy in two.
Ryuko calls to Senketsu for help, and Senketsu's spirit sends down the Scissorblades from space.
Inumuta's devices detects the Scissorblades entering the atmosphere at high speed.
Ryuko absorbs Life Fibers into her own being (which is why her hair is streaked red).
Senketsu shines in the sky.