There's a BUNCH of stuff going on in Kill La Kill, Trigger's surface stuff and trope exploration, made famous with Gurren Lagen, and their trademark Over The Top... everything... is in fine form here, with magical girl anime and their traditional fetishistic/exposing transformation sequence and costuming being one of the most pointed and obvious skewers from square one. Comedy, action, fan/manservice all of this stuff is on display at the surface and can be incredibly distracting from the central theme of the anime.
It all comes down to CLOTHING! I know it's hardly a shocking revelation but it's not in the way you're thinking. It's clothing as a social device that's the central theme here. Remember a lot of Japan is pretty damn clothing concious, Tokyo is one of the fashion capitals of the world and how you dress, and what labels you're wearing can be damning in certain circles, to a further extent then the version of this behavior you see in the U.S. with the epicenters being the American fashion capitals of Los Angeles and New York City.
Take a second and think about your clothing, think about your favorite shirt, your favorite pants, skirt, shoes, what do they say about you to an outside observer? Do they communicate anything in particular? You might not think they do, but when you take a step back and examine your mode of dress you are in fact telling people that you belong to certain groups. Whether it's based on passions such as anime, firearms, video games, the types of music you associate with, rock, punk, rap, or you just happen to only wear a certain brand whether it's Hot Topic or American Eagle. This has been an inescapable facet of human culture for centuries, since we first put clothing on. Ragyou even goes into what we were befor the fibers got their... uh... fabric on us, naked apes, unaware of their nakedness, much like Adam and Eve in the Garden of Eden, now obviously clothing (or life fibers) didn't influence our actual evolution BUT they did influence our social evolution.
From earliest man on clothing, whether it was the red cloaks of the Roman Legion, or the simple jewlery of our further ancestors have been used to distinguish groups within society, while the shape of that society's clothing over all distinguishes that culture from others, fighting against that grain by dressing differently, by adopting a different culture's dress or that of an extreme sub culture (say the Punk style compared to general Western clothing) will get you looked at different and looked down upon by many people.
This social pressure based on how we dress and what we look like, how we present ourselves to those around us, is simply put, conformity. It's subtle, the desire to conform and be like everyone else, it can be lonely on your own, and going with the crowd, not swimming against the current of the social wave has it's benefits doesn't it? Think about what the main wave in your local area wears, in particular think back to High School, when that sort of thing was closer to the surface. For my cohort American Eagle, Nikes, Rebok and a few other "main" brands were what you wore if you were part of the main "group". Ragyou's "Revocs" corporation is set to be just such a brand, albeit on a dominating global level.
So as human beings a very real part of our self identity and personality is caught up in how we dress, how we present ourselves to the world around us. It's why in the United States students fight against dress codes under the concept of freedom of expression (which falls under speech).
Enter Ryukou Matoi and her scissor blade. From the word go she's dressed differently then everyone around her, her flash of red in her hair distinguishes her as well. From the first time she steps on to the grounds of Honnouji Academy she's challenging the social order and rebeling.
This brings us to the central theme of Kill La Kill. Revolution. Not political revolution, but individual revolution. The personal rebellion where you stand up and chose your own path in life. Fighting against the the current and resisting the easy road. Hell the anime LITERALLY tells you every episode with the refrain of "Don't Lose Your Way"
So what happens when everyone is their own revolution? Culture changes. A species changes. At the very least you will change for the better. Within Kill La Kill we see multiple forms of revolution, Satsuki's "change from within the system" playing by her mother's rules while preparing the minds and wills of those who follow her to resist, snd Nudist Beach who take the path of forming an extreme counter culture to fight against the main stream. However as Ryoko fights on, more and more individuals have their own personal revolutions and realizations, the theme of revolution becoming even more obvious once the curtain comes off Satsuki's plan to resist Ragyou's plots with the life fiber aliens. Even Senketsu under goes a personal revolution in how he sees himself, and his place in the world by the end of the anime.
So final word, what is the message of Kill La Kill? What theme does it truly want to present us? IMHO it's just four simple words that I mentioned earlier...
Don't lose your way.
