The setting in general is actually pretty chilling. Civilization as we know it has completely collapsed, and 90% of the world has been rendered a toxic, lifeless wasteland. The few pockets of society that remain are uniformly despotic hellholes run by fascists who dictate their people's survival solely by their worth to whatever demented cause the leaders have. Honnuji itself is a crime infested, poverty stricken hellhole where your status in society is literally dependent on the unpredictable whims of the city's school's Student Council, who all possess magic uniforms that grant them godlike power and authority. Those who cannot afford Star Uniforms are effectively slaves. The first five minutes an innocent man, who just wanted to improve his miserable life, hunted down like a dog, tortured, murdered, and having his broken, mangled corpse impaled on a banner for all to see.
Technically. This only really applies to the Honnō and possibly the surrounding area. The world is actually perfectly fine, considering that Ryuko isn't familiar with ridiculous things (that aren't Life Fibers) she encounters when she reaches Honnō. Later on in Episode 24, when the whole world is getting consumed by the Life Fibers, we see that the rest of the world is pretty much identical to ours, at least the cities.
That being said, it's pretty apparent that the government of Japan specifically is entirely useless. The country is divided into city-states. The Kiryin, and, to a lesser extent, Takarada conglomerates do pretty much whatever the heck they want on their own turf and get away with everything, and since they only maintain order where it benefits them, crime flourishes in every shadow. The citizens are way past Bystander Syndrome and have become living manifestation of Comedic Sociopathy: they barely bat an eye at random violence and pretty much treat it as an accepted fact that they have to band together and fend for themselves if an aggressor comes their way. Schools have become heavily militarized, making the Honnouji academy barely any more dictatorial in comparison.
How Senketsu's transformation looks from the outside◊. First he begins to bloat up creating what seems to be teeth around the openings (sleeves, neck, bottom of the shirt, upside of the skirt, frills of the skirt). Then he bloats up even bigger with Ryuko visible in his mouth. Then he seems to jam his mouth shut with Ryuko's head and hands sticking out between his "teeth". Then he presses himself together vertical and then horizontal still with Ryuko visible. Finally he forms into her combat outfit, his teeth disappearing. All while blood is spitting out. While it doesn't seem to be all too painful, Ryuko looks visibly exhausted. Both members of the student council witnessing it are a bit disturbed. The transformation sequence after Ryuko fully "accepts" Senketsu looks considerably less painful until Ryuko's berserker rage, that is.
Ironically, Senketsu himself is tame and even protective of Ryuko, while Junketsu (and by extension, all other known 100% life fiber clothes) is constantly trying to consume Satsuki, requiring a lot of mental strength by her to be tamed and to be pinned behind a glass wall when not worn. Episode 5 gave a short hint on what might happen if Satsuki would lose the struggle with it.
Which puts Satsuki's struggle with Junketsu in the previous episode into a whole different perspective. Unlike Tsumugu's friend(who later revealed to be his sister) who had to be in a certain mindset to be overpowered by her uniform, Junketsu apparently tried to consume Satsuki right away.
It gets to the point where Satsuki can't wear Junketsu constantly like Ryuko and Senketsu. She has to trap Junketsu inside a display case and pin it down or else it'll try to consume her again.
Episode 16 puts the above into a whole new light: turns out the Life Fibers are an extraterrestrial life form, and Ragyo has woven dormant ones into all REVOCS clothing. Nobody knows what will happen when they're woken up, but Tsumugu compares it to people fattening up cattle...meaning this could happen on a widespread scale.
Nui in general, really. She doesn't move in fluid motion, sliding in and out of frames, whilst spilling poisonous dialogue with an unmoving smile and cutesy voice, showing how truly inhuman she is. Not to mention, her presence puts Satsuki, of all people, on edge.
In some shots, it's clear that her neck isn't connected to her spine, and the "horns" coming out of the top of her head are actually her bottom teeth.
Then she gets the Cool Down Hug, and everything's better! Except instead of a quick, sparkling change back; we see in black-on-red silhouette as her body very slowly twists itself back into a proper shape, wth more groaning and sobs of agony, and the very unsubtle popping and snapping of bones and ligaments as they are reshaped properly.
On that note, we can cheerfully add Paranoia Fuel to this list. Where will Nui Harime turn up next, and in what form?
Pay attention to Nui while she is being confronted by Satsuki. As they are still talking, Nui is still lowering the blade. She could have killed Ryuko if it wasn't for Satsuki finally convincing her to leave.
The Paranoia Fuel is reinforced in episode 16 when we learn that Nui was in Osaka all along, piloting Satsuki's helicopter. That's right, if she felt like it, she could have easily joined the battle.
In episode 16, Ragyo "purifies" her daughter. Well, she says she's purifying her, but the whole scene is basically sexual molestation (fingering).
It's made even worse by the look on Ragyo's face just before the "purification" starts, which can only be described as predatory. And even worse by Satsuki's reaction right beforehand...this has obviously gone on for a long time.
Ragyo's maniacal expression in episode 17 after Satsuki impales her on the stadium roof, combined with the fact that she's frothing Blood from the Mouth, is perhaps her most disturbing yet.
And let's not forget the image of a stadium full of teachers, parents and siblings, including Mako's family, being forcefully cocooned by their own clothes in preparation for consumption.
Also worth noting: COVERS has gone haywire following the unsuccessful efforts of Shiro and his men.
Honnouji post Time Skip is not pretty. Ragyo and the Original Life Fiber now control literally everything in the city, COVERS openly stalk the streets searching for humans to devour, much of the population has been enslaved, and the few that remain free live in constant fear of a COVER coming up behind the corner and killing them.
Not just the school and the town. With the fall of the Northern Kanto Gang alliance, the entire country has fallen to Ragyo and COVERS. Even worse, it seems that Nudist Beach was preparing itself to fight to the bitter end despite being severely outnumbered.
Whenever the COVERS absorb someone, that person is reduced to a shrivelled skeleton who can only emit feeble, high-pitched screams.
That sound as Soichiro dislocates his spine and shoulders to complete the transformation into Prof. Matoi.
The fact that Satsuki has spent a monthas a prisoner, suspended naked in a cage underground, being psychologically, physically, and sexually abused by her mother.
Then it's revealed the only reason she kept her alive was so that Satsuki could be the power source for a giant Kamui.
The ending of episode 19. Ryuko has well and truly snapped.
Even before that, Ryuko's grin as she gleefully runs Nui through. Keep in mind that this is supposed to be a normal high school girl. She's snapped to the point of enjoying brutally murdering someone. Then again, Nui did kill her father, so it's not too hard to understand.
Nui pulling out her own heart to show Ryuko that they're both human-Life Fiber hybrids.
Episode 21 has Ragyo and Nui having what seems to be a threesome with Ryuko to complete Junketsu's takeover of Ryuko's mind. The take over is so complete that the first thing Ryuko does afterwards is stick her tongue down Nui's throat. The episode also implies that Nui may be in love with Ryuko, which, given Nui's personality, can only be a bad thing.
The previous episode hinted at an epic clash between Ryuko and Satsuki. Instead we get an absolutely horrifying beatdown as Ryuko systematically destroys every strategy and ability Satsuki tries while giving a Breaking Speech about how weak and useless Satsuki is. Normally Satsuki would respond with her own Breaking Speech, but this time she never manages anything more than pained grunts as she desperately tries to stay alive.
Ryuko, after having undone Junketsu's brainwashing, proceeds to tear it off her body. An act that can be likened to ripping off your own skin with as much blood spraying as such an act would cause.
Episode 22: Nui completely snaps after having her arms lopped off by Ryuko, trading her cutesy smile for a permanent Slasher Smile. Her eyeball even gives off a sickening squelching sound when moving.
The sudden Nightmare FaceNui gives Mako.◊ And every one after that, especially her expressions while her arms sprays blood on Hououmaru expressionless face - first she has a completely manic expression, and then when Hououmaru warns her about Ragyo's possible reactions, Nui's face becomes terrifyingly blank briefly, as she rejects the possibility of needing to explain her predicament.
To say nothing of what happens when COVERS start attacking Aikuro's ship.
Nui frantically sewing with her teeth, a murderously crazed expression on her face. Extra points for the slouching and limp-looking mind-controlled members of the Sewing Club surrounding her.
Satsuki's explanation of the ultimate goal of the Life Fibers is pretty chilling. In a fashion kind of similar to the infamous Lavos or the Phazon, the Life Fibers ultimately intend to cultivate intelligent life into suitable hosts before consuming them, and then turning the planet into an explosion to propagate across the universe. Not only are we cattle to them, they also treat the planet itself as an expendable resource.
It borders on Fridge Horror, but Ragyo could easily match Satsuki and Ryuuko who were using their Kamuis to the fullest while she herself didn't have one. Except now she is clad in the ultimate Kamui.
There's one final act of creepiness on Nui's part as she gleefully decapitates herself and fuses with the Life Fiber barrier around the satellite uplink to form a giant freaky Life Fiber version of her face. Just in case that wasn't enough, this is proceeded by Nui referring to Ragyo as "Mama" for the first and only time. And the actual decapitation happens to a background of hearts. Finally, for added Squick, all of Nui's clones do the same for no reason.
Nui's disposition in this episode is HORRIFYING. Her normally sunny attitude is replaced by sheer hatred for everyone and everything around her. Her eyes go from bright blue to a sunken-in gray with popped blood vessels, and she bears her sharpened, twisted teeth into a scowl.
Ragyo rips her own heart out in the same manner she did to Ryuko earlier and crushes it, causing her to explode into Life Fibers.
There are Life Fibres scattered across the galaxy, and it's entirely possible that they could find Earth again... an Earth that has no Goku Uniforms or Kamui left to fight them off with.
Ragyo is just as terrifying in Rei's flashback as she was in the present. There's something about seeing her not even flinch as panicked soldiers riddle her with bullets in a vain attempt to stop her advancing that makes you outright fear her.