The thought of whatever happened to Yuya after presumably going into Helheim Forest.
Helheim Forest itself is rather creepy. Everything comes in inverted colors, there are Inves monsters roaming around at every turn and people even get a sinister temptation to eat the fruits off the trees and plants.
The Unknown Girl who appears to give cryptic warnings to the Riders saying that You Can't Fight Fate, they'll have to fight to the bitter end and there's no turning back. Mitsuzane's particular response saying that he'll suffer and bear the burden as long as Mai notices him doesn't mean good things down the road for the kid.
The most she can tell Mai about the fate awaiting her is to boldly encourage her to leave town.
Any time Mitsuzane reveals his ruthless side. It's quite jarring to see how quickly he can go from a sweet kid to a manipulative cutthroat who will do whatever it takes to get what he wants. It's even more jarring to see him and Sid actually getting along because of it.
#4: Zangetsu's ruthless Curb-Stomp Battle against Gaim. The fact that a powerful Armored Rider comes at Kouta with the intent to kill him is enough to break our hero. It gets worst when you consider that Kouta could've been killed in Helheim Forest and no one would know about it.
Zangetsu:This world is filled with evil. Evil beyond purpose or reason.
#6: Oren. Just Oren. In his debut episode, we learn that he's a flamboyant baker. Then we learn the fact that he's a retired solider meaning that he's killed people on the battlefield before. And let's not forget that he has sadistic and homicidal tendencies as well. While he provides a certain amount of comedy and fights for the thrills and entertainment, we can't forget that he nearly attacked the defenseless dance members of Team Gaim just because he was annoyed with them. It's scary to think how much damage he could cause if he got serious and actually went out to kill people.
And to make matters worst, this guy has gotten a hold of a Sengoku Driver, he has no problems with beating Armored Riders (who are teenagers) into violent submission and the Yggdrasil Corporation is perfectly okay with that.
Granted, Takatora is violently against letting Oren keep the Driver and immediately recognizes the danger he poses.
#8: Near the ending of the episode when a man is suddenly dropped in an allyway and the camera pans up to reveal a strange Komori Inves hanging off a wall. Then it's followed by Mitsuzane's Wham Line.
Mitsuzane:Mai got stranded in the forest, right? What if an Inves came from there and got stuck in our world the same way?
#9: The first minute of the episode. A worker is walking around a factory and spots the fruits of Helheim growing. Picking one of the fruits off, he goes into a hypnotized trance and says "It looks... so... delicious...". Later in the episode, Kouta finds the hard hat of the worker covered in leaves. Considering recent events, it's highly likely that the worker became the Komori Inves that terrorized the town.
Also, when one of the Yggdrasil workers fires his flamethrower at Kouta and Mitsuzane. You see the flames coming right at you in first person.
#11: Kouta's speech at the end of the episode.
Kouta: Looking back on it, that was when the gears were starting to turn. But... we really didn't realize anything at all. We didn't know that our fates were already written in stone. We just wanted the power to reach our dreams, we thought that would help us grow up. That's what we all believed, at least. But... you can't wish yourself into growing up. You grow up when you can't be a child anymore... In the endless war that has yet to come... we would discover that for ourselves...
#12: The debut of the Energy Lockseed for Zangetsu. And he looks like he's ready to kill!
Another from the twelfth episode is when it's implied that Yggdrasill has spies everywhere. It's the waitress at Drupers. She seems to listen in on Kouta and Micchy’s conversation, suddenly appears behind them and keeps throwing them eerie looks.
Mitsuzane channeling his Kureshima side again, but this time his unsettling behavior seems to last through the entire episode. Not only does he try to pressure Kouta into giving up his belt, his whole character development seems to head backwards when he twice chooses to just watch innocent people get attacked by Invase rather than use his own Sengoku Driver, and even tries to force Kouta to not help.
#13: People injured by Invase are getting sick due to some sort of bacteria leaking off of the monsters...
Yggdrasill fully anticipated this. And while the members of the inner circle casually discuss their plans, people in the hospitals are screaming and suffering. The contrast is rather off-putting.
Hase holding a Helheim Fruit and looking like he's gonna eat it in the preview caused some frights considering the wild mass guess that the fruits turn people into Inves... AND IT'S CONFIRMED! Worse yet, as of now there seems to be no way to transform people back. And considering that our heroes only ever cut Invase down, things are not looking good for Hase.
From the looks of things, Hase's on the brink of falling into despair, and given last season, there's the haunting fact that even if Hase didn't eat that Lockseed, he would've turned into a kaijin anyway.
Hase's half Invess form. Imagine an Invess with a human face.
Also, as it turns out, the Komori Inves from the ninth episode is most likely the construction worker who found the premature Lockseed at the beginning of the episode.
Recall back in episode 1, Kouta got hurt pretty badly by the Inves before he finally transformed, and there's the fact that only a SINGLE hit from an Inves can make people contract the disease.
People can breathe easy, since according to the Wikia, The Inves know about the disease and can control it, only choosing to infect others when they need more immature Lockseeds... Which most definitely means Rat is infected.
Everyone relax. Rat's not infected, just beaten the hell up. The doctors gave him the all clear.
#14: It gets far, far, FAR worse. Look at Hase's Inves form, Hekija/Bixie Inves. It looks eerily similar to the Byakko Inves from the first episode with the green and white "skin", as well as it's right arm having a claw and it's left being more "human." If this isn't a coincidence...then we finally know where Yuya went...
To that dimension where defeated kaijin go. Yuya ate a premature Lockseed, and became the Byakko Inves. As in, the same Inves Kouta killed in his first fight as Gaim.
Rewatching Gaim's first fight was disturbing. The video had no sound, without the sound effects, Kouta's voice or even the BGM, it felt less like a KR show and more of a snuff film, not helped by the fact we know Kouta just happily killed his friend without knowing
#16: Takatora decides to show Micchy something in the Hellheim Forest that causes him to collapse onto his knees in shock and horror. Just what the hell did Micchy see?!
Take a look at the tree◊ behind and to the right of Micchy. The small ... things on the tree looks disturbingly like human mouths.
During the zoom in on Micchy's eye, you can just see what he's seeing. It appears to be ruins of some kind.
#17: Part of the episode has Kouta's sister get kidnapped, though there's the fact she DOES work for Yggdrasil, so it might simply BE some type of set-up.
Thankfully, it is. It turns out to be Yoko in disguise.
#19: The title of the next episode in the preview gives off a very scary vibe. "The Invasion Begins with the End of the World".
#20: Kaito shows a very disturbing side to him. He declines the offer to join Yggdrasill despite them showing him, they really were saving the world. He doesn't decline for moral reasons, or even revenge. He declines as he REFUSES TO SAVE THE WORLD. He thinks a world that needs lies to survive should be destroyed. He even calls the invasion a good thing, thinking that only those that can fight should survive.
And this is followed by Sid, Ryoma, and Yoko laughing and revealing that they think exactly the same way. Not only does this confirm that these three are completely insane, but then you realize that these are the people Takatora is relying on...
In a previous scene, we see an Inves victim growing vines from his wound. While we've already seen other infected before, this is the first time we're actually treated to a shot of seeing the disease grow.
What about the story behind Helhelm itself? As Takatora puts it best: "Evil without reason or purpose".
And that story is the seeds came from a different dimension and completely took over the dimension that is now Helhelm. Every animal is now an Inves, that includes the humans. Takatora states Earth has ten years before the same thing occurs
And guess what? It's happening in the real world too, in the form of invasive species. No, not to the extend it will cost human lives but invasive species had caused damages to native ecosystem and some even damages human infrastructure.
#21: Bonefide human criminals used Inves to steal from an armored truck. Then again, they might have been part of Sid's plan to break Kouta and get him alone, but still!
The ring around Yggdrasil's tower? At Takatora's command, it can completely destroy Zawame in an instant.
Sid's smile when Ryoma lets Sid attempt to kill Kouta.
#22: We learn that Project Ark is the mass production of the Sengoku Drivers so humans can survive in the Forest. That's nice and all, but we learn Ryoma can at most make 1 billion. So 6/7 of the human race will die, and that's not the disturbing part. Ryoma tells Kouta, as the remaining humans will become Invess, the plan is to kill off the humans that can't get belts, all the while being completely calm when telling Kouta.
Similarly Kaito knows about the plan to nuke the town, and doesn't care at all. Meaning he is fine with Team Baron dying just so he can get unrivaled power
#24: Mitchy's mindset has become very unsettling to see. He, like Kaito, is obsessed with power, but instead of brute force like Kaito, he instead just desires the power to influence. And his reaction to anyone that doesn't listen to him is a Death Glare. He has thought the best idea to get Kouta to listen to him is for, "The idiot to get hurt some more".
Kaito meeting Mai, he somehow gives Morality Pet a creepy turn. He meets Mai to pretty much state that, if after facing an unstoppable force that cause her to despair and she can still dance, then he'll respect her.
#26: This episode just shows how far Micchy and Kaito have fallen. Micchy is now willing to summon Invess on innocent people and the Beat Riders (including Mai) just so everything works in his favor, and his Death Glare is more or less his new normal face. As for Kaito, he basically tells Zack, "Yes, I am working with the people that are trying to kill everyone. I don't care, good luck trying to survive," to his face without any trace of remorse.
#27: Mitchy is now willing to shoot Kouta. While the latter is unmorphed and unconscious
#28: Mitchy just stood there, watching Takatora fight against and get killed by Marika, Sigurd and Duke! Micchy just watched his older brother be picked apart!
Honestly a lot of what Micchy does this episode is pure Nightmare Fuel but this is what really takes the cake: Him essentially stealing his brothers name and identity and use it in what is basically a first degree attempted murder done solely to spite both his brother and Kouta for ridiculously petty reasons and the way the murder attempt plays out is what really sells it. Micchy uses none of Gaim's campy fruit powers to mitigate the shock factor. He was going to beat Kouta to death with his bare hands exactly like something out of a slasher movie...Ladies and gentleman, after over ten years of bad knock offs and bad popularity cash-ins Ouja has finally found a worthy successor in the form of Mitsuzane Kureshima as Zangetsu Shin II.
The reason that Micchy turned on his brother? Because Takatora praised Kouta. You could literally see the venom oozing off of him. Even his thought processes show signs of outright hatred of Kouta. "Kouta ruins everyone he comes into contact with."
It was hinted at before, but this episode shows just how dark Kouta's rage can be. When Zangetsu Shin II summoned a bunch of Inves to run away, Kouta proceed to beat the Kamikiri Inves with his bare hands. No styles, no one liner, no poses, just straight up beatdown.
#31: Roshou pulls off what is perhaps one of the most (if not the most) gruesome death(s) of the previous Heisei Rider shows. How? How does crushing Sid between two cliffs sound? Yeah, the guy had it coming, but that still doesn't discount it for being this moment.
#32: Redyue proceeds to push things into an absolute worst case scenario. She reopens the crack in Yggdrasil's base, sends an entire army of Invass through, and covers the entire tower in Helheim vines. This, on top of the city-wide communications blackout, leaves our heroes in quite a pickle.
What makes this more unnerving is that she's walking with Micchy and casually talking to him while hordes of Inves follow them. It's like something out of a zombie movie.
Kouta is hinted to be losing his sense of taste. If you watched Kamen Rider OOO, you know what may be coming.
#34. Kouta sees Akira taken away by an Inves, due to an Sadistic Choice between saving her or a little boy. That's only small compared to the ending. Between the multiple missiles headed towards the city, Roshuo FREEZING them before impact and making them vanish as it was nothing, and Micchy laughing again, this one is truly a Wham Episode and a grim view of what to come.
#35: Micchy takes delight in kicking and punching the crap out of Kouta unmorphed, and thereafter attempt to shoot his former best friend down as Zangetsu Shin.
Speaking of that attack, if you pay close attention, this would've been when Micchy killed Kota if he didn't turn into Gaim. He was mere SECONDS away from doing Kota in.
The entire revelation becomes all the more horrifying when you realize that Micchy's Face-Heel Turn comes completely out of nowhere for both Kouta and Takatora. From Kouta's POV, he was just talking to his best friend when said friend suddenly attacked him and revealed that he's the one who's been trying to murder Kouta for the last several episodes. Takatora suddenly finds out that his younger brother, who he genuinely loves and wants to protect, has become a murderous supervillain. Both men see someone that they love become a monster out of hatred and jealousy; imagine how utterly terrifying that would be.
It's subtle but, when Takatora saw Kota, Yoko and Kaito on their way to save the kidnapped people from the Overlords, he thought that Ryoma sent Yoko to spy on, and betray Kota's group.
Micchy's reaction when Mai tells him that she's chosen to stand by Kouta since he refuses to give up hope:
Remember last episode, when all those missiles were about to destroy Zawame City, but Roshuo stepped in and stopped them? Thing is, he didn't disintegrate them, as it had appeared; he simply moved them, and it turns out they devastated America instead.
36: Redyue, unsurprisingly. She admits to having killed her family in the past and that she found the feeling of betraying and toying with people who trusted her so much was exhilarating.
Even worse is the fact that It's hinted that Mitsuzane might be starting to feel like that as well.
Kaito ends up getting a cut from Redyue, and it glew green... meaning he's got that Helheim virus that the Inves were sending around
A more subtle example is that there is Helheim fruits growing everywhere in every scene! The invasion is almost complete.
This time, we got explicit views of famous monument - Statue of Liberty, Forbidden City - being covered in Helhelm vines, with numerous Inves dropping out from cracks.