Zero-One’s main color being yellow may seem strange… until you realize the yellow parts actually glow in the dark, which turns them green and thus matches Kamen Rider 1’s color scheme even more.
On the subject of names Vulcan and Valkyrie are also this given that their Transformation Trinket is also a gun.
Vulcan shares his name with a gatling style rotary cannon, the M61 Vulcan.
Valkyrie however shares her name with ammunition for assault rifles, the .224 Valkyrie.
Can also be considered Fridge Horror as well: the Rider after Zi-O is about dealing with AI going berserk. It was never revealed how exactly the Humanoise came into existence, did we?
Yes, the text blurbs at the end of every jingle might be a bit Narmy, but between them and the initial activation sound, which is revealed to be that key’s unique ability, you realize that each Progrise Key tells you A) What it’s useful for, and B) How best to do so.
Assault Wolf when used in tandem with the Assault Grip. The text-to-speech makes it clear it’s a Deadly Upgrade for any human who uses it, considering it was designed to be used by HumaGears. It also doubles as Exact Words when you think about it. “No chance of surviving,” referring to both the unlucky sod who is fighting the person using Assault Wolf, and the user themselves who are literally willing to risk their lives to bring the enemy down. As Isamu’s section of the A.I.M.S. Character Page points out, it’s like making a Deal with the Devil.
On the other hand, Shining Assault Hopper elicits a different reaction. With Assault Wolf, it seemed like the Ark was giving Isamu its power, but with the explicit statement in the text-to-speech portion stating that he’s just as likely to die from using it as are his opponents. With Aruto, on the other hand, both Zea and the Ark work together to help create the armor that will be the Shining Assault Hopper form. In the second text-to-speech portion of the transformation, the driver says “No chance of surviving this shot.” It could be because Aruto is the grandson of the man who made the Ark, but it’s far more willing to help Aruto to the point it works together with Zea to help him than it does with Isamu.
Even Metal Cluster follows suit, albeit more subtly. Its ability Everybody Jump references it's powers as a Pest Controller, given that the armor of the suit is made of Cluster Cells (Something also referred to via the standby jingle "Let's Rise"). Meanwhile the actual lines "Secret material, Hiden Metal", and "It's High Quality!" both detail the sheer durability and strength of the form given that it's made entirely of the metal, though given how unpredictable it can be (and given that the Ark has a way in if Aruto has hate in his heart), the form isn't a normal one Zero One would have access to.
Everybody Jump takes on a new meaning after all the humagears send Aruto their love and positive emotions. They're all jumping with him.
The fact that it sounds like an ad makes sense as it was made by Gai.
Jin's new Key follows suit as well. It's ability, Inferno Wing highlights that while it also grants flight likes it's sibling, it also coats every attack and action with intense flames. So intense in fact that the text line straight up informs you what you're in for with The strongest wing bearing the fires of hell.
So, who does have Speed for its ability? None other than the Lord of Speed himself, Kamen Rider Kabuto.
A meta-example. The meaning behind the name “Reiwa” is “Beautiful Harmony.” The story of Zero-One is about humans coexisting with A.I., or in other words, living in harmony.
Most weapons in this series fold out of attaché cases. Fitting for a series featuring a company president Rider.
The Magia are all based on extinct animals, symbolizing their goal to render humans extinct.
The Battle Magia are based on horseshoe crabs, which are living fossils, and they only appear in an alternate timeline where Humagears have succeeded in their uprising.
So far up to #8note (#9 features a Giger instead, and notably, #10 onwards appears to be devoted for plot instead of making a reference, however, the theming could still return in the future.), each of the Magia are tied in some way to the victim they were created on, or the episode they are in.
The Berotha Magia in #1 is created from a comedian HumaGear. Berotha’s design is based on an extinct praying mantis species, specifically Kujiberotha teruyuki. A species named after a Japanese actor who is also known for his comedian roles, Kagawa Teruyuki.
The Kuehne Magia in #2, who was created from a delivery man HumaGear, is based on an extinct flying reptile, the Kuehneosuchus. Being able to fly and stick on walls would be really useful for a delivery man.
The Ekal Magia, also in #2, was created from a security guard HumaGear. Ekaltadeta is an extinct species of marsupial. Marsupials carry their children with them, guarding them from threats.
The Neohi Magia in #3 is based on Neohibolites, an extinct genus of squid, and was in an episode featuring a sushi chef HumaGear making squid sushi.
The Onycho Magia in #4 is based on Onychonycteris, an extinct species of bats. “Bats” sounds similar to “Bus” when both are pronounced in Japanese. The HumaGear this Magia is created from is a bus driver.
Another Onycho Magia appeared in #6, this time created from a taxi driver. However, it only appears shortly before getting destroyed, as its only purpose was to steal and deliver a Progrise Key to Jin. It is likely that the production team for the series chose Onycho Magia due to Kamen Rider Jin debuting in the same episode and using the Flying Falcon Progrise Key, which also debuted in the 4th episode.
The Vicarya Magia in #5 is based on Vicarya, an extinct genus of snails, thus it features drill-like shells. Which also happen to resemble the tip of a pen or a brush used for drawing and coloring manga, which is what the episode’s plot is centered on.
The Gaeru Magia in #6 is based on Rheobatrachus (also known in Japan as “Ibukurokomorigaeru”), an extinct genus of frog that is known to raise their young by carrying them inside their body to protect them. Frogs are also an animal known for their voice. These two facts match the theme of the episode, which is a protective parent raising a voice-acting HumaGear.
The Mammoth Magia and Dodo Magia in #7 are tied to a more simple but also slightly more obscure theme within the episode: Hot and Cold. Mammoth is an animal that lived in cold places, while Dodo is an animal that lived in a hotter tropical island. The theme is reinforced by the two auxiliary Progrise Keys that Zero-One uses in this episode, Flaming Tiger and Freezing Bear, not only having hot and cold powers, but also using an animal commonly found in hotter tropical/savanna regions (tiger), and an animal that lives in the Arctic (polar bear). Also, Kobe, the HumaGear featured in the episode, is referred as hot-blooded, yet dresses fully in blue, a cold color.
The Dodo Magia returns in #8 as the only Magia in the episode, however, it still ties into a theme of the episode, as the Dodo Magia is an assassin dressed in black, while Mashiro-chan, the HumaGear featured in the episode, is referred to as an angel dressed in white.
The Hiden Zero-One Driver containing a built-in tutorial serves to not only explain its functions to the user but possibly guide them through the battle.
Each Transformation Trinket has a different type of announcement for Progrise Keys, showing how the users of each device relate to Hiden Intelligence.
The Hiden Zero-One Driver starts with a jingle, announces the name of the Progrise Key, and ends with the text-to-speech portion, showing how Hiden Intelligence created the technology and Zero-One is the intended user of it, as well as how he embodies the entire spirit of the tech being used as a force for good and a positive image (hence the light-hearted jingles), but also as a tool to fight the Magia (the text-to-speech).
The A.I.M.S. ShotRiser announces only the name of the Progrise Key and the text-to-speech (with the latter being partially drowned out by the sounds of gunfire and explosions), showing that while they also fight the Magia, they don’t have a positive relation with Hiden Intelligence, and only see the Progrise Keys as a soldier’s tool to destroy the machines, hence the shortened announcement.
The ZetsumeRiser only announces “ZetsumeRise,” because the Magia are just interchangeable monsters that want to make all humanity go extinct, and the belt breaks the key rather than opening it to draw its full power out. Unusually, it does announce the name and text-to-speech portion of Progrise Keys, but not Zetsumerise Keys, which just play a twisted sound effect.
Similar to the above, the ForceRiser announces “ForceRise,” and ends with a distorted robotic “Break Down,” showing that they’re directly opposed to Hiden Intelligence and only care for the Keys as much as they can cause destruction. The belt itself opens Keys without authorizing them and so doesn't get full power out of them (but more than the ZetsumeRiser does), also shown in that the armor looks unfinished and held together by straps. Also like the ZetsumeRiser, it plays the text-to-speech portion of Progrisekeys, albeit drowned out by the “Break Down” voice (notably when Aruto uses a ForceRiser out of desperation with Rising Hopper), but Zetsumerize Keys just play the same twisted sound effect and no voices.
The ZAIA Thousandriver plays the full jingle of Amazing Caucasus and Triceratops, which has no text-to-speech (instead ending with ”Presented by ZAIA” and ”I am the President!”, respectively), because Thouser acts heroically but is a self-aggrandizing competitor of Zero-One and Hiden Intelligence. With keys other than the ones Gai (and later Lyon Arkland) specifically designed for it, it just announces ”Breakrise! (name of key's) ability.” and absorbs their power rather than initiating a transformation.
The RaidRiser uses the exact same announcement style as the ZetsumeRiser and ForceRiser, because they're the human equivalent of the Magia. It likewise doesn't open the Key and doesn't draw out its full power. The Key's text-to-speech announcement is partially drowned out by sirens and static sound effects.
The ArkDriver, like the Zero-One Driver, uses the full jingle, Key name, and text-to-speech portions, but its own voices are distorted and sinister. Ark was created by the same man who made the Zero-One Driver, but the Ark turned out to be evil, and so the ArkDriver a twisted reflection of it. In the series, it's only used with keys whose voices are also distorted and sinister (Ark-One, Ark Zero-One, and Thousand Ark).
The CycloneRiser with Rocking Hopper announces the Key’s name and “Type-1,” showing it is a prototype belonging to an apparent enemy of humans. Played with in that when Rocking Hopper is used in the Zero-One Driver, the Key's full transformation announcement starts with “The sole hero of j-j-j-justice!” and ends with “Kamen Rider will fight to protect humanity. Type-1”. It was meant to be a heroic power, but the CycloneRiser was corrupted by Ark.
In general, there are three types of announcements from the Keys, depending on how they're used. The Zero-One Driver and its variants, the ones that authorize and properly draw out the full power of the keys, use the full transformation sound; the ShotRiser and its variants, which also properly authorize and open the keys but are mostly used by police and military, use a shorter more perfunctory announcement to get into the fight more quickly; and the ZetsumeRiser, the ForceRiser, the RaidRiser, and the CycloneRiser, which either don't open the keys at all or don't open them with authorization, have an even shorter announcement for Progrisekeys and no announcement at all (other than the belt name) for Zetsumarizekeys.
Isamu’s arm being in a sling in the end of #2 makes sense, and not just with him forcing the Progrise Key to open up. In the first episode, the A.I.M.S. ShotRiser’s recoil can be seenknocking him back a bit. It likely means he’s using a higher caliber weapon than he’s used to and probably had minimal training, thus probably not handling it completely right. And not only did he use it one handed after stressing his arms out to open the Shooting Wolf key, but he fought an extended length with it, even using a Shooting Blast. It’s little wonder why his arm needs time to heal after all of that.
Isamu’s main form is Werewolf, while Yua is Cheetah. Their contrasting personalities are basically Dog vs. Cat.
The MetsubōJinrai ForceRiser requires the Progrise Key/Zetsumerise Key to be inserted while closed, with it being forced open by the driver’s activation. It’s aptly named.
Isamu’s problems with opening his Progrise Keys may actually be explained by how the Progrise Keys are supposed to be used — both the Hiden Zero-One Driver and the A.I.M.S. ShotRiser have an additional step (holding the Progrise Key over the Authorizer, and pushing it into the Rise Slot before unfolding) that makes the Driver announce “Authorize” before the more elaborate sounds. Something that Isamu’s been skipping over all this time.
The first time he transformed, he was expressly forbidden from using the key (and so not authorized at all), which is why he forced it open. After that, it seemed it just became a habit and a quirk of the character.
One of the most common tropes in Kamen Rider series is the evil brother/father figure. Horobi technically fills the role as he considers Jin his son.
Why Aruto cracks more bad puns while transformed than not transformed is explained in #1, where it was shown that the Hiden Zero-One Driver gives the wearer the same mental processing speed as an AI supercomputer. Of course Aruto would use it to come up with, and then make jokes.
Why are no specific reasons given for why HumaGears based on real people are illegal without obtaining permission? Because the most obvious one couldn’t be said on a kids show.
Other possible reasons could include identity theft or fraud.
It may not be obvious at first glance but the reason the Mammoth Magia loses to Zero-One’s Freezing Bear form is because mammoths went extinct at the end of the Ice Age.
Just like the Hiden Zero-One Driver, the MetsubōJinrai ForceRiser summons a projection of the Progrise Key’s Rider Model animals during transformation. What makes this brilliant is HOW the animals react to being forced to release their power, before they are shattered by the armor forming.
Flying Falcon envelopes Jin with its wings, which can be seen as either an attempt to calm down and comfort Jin (who turns out to be not as bad as Horobi), OR an attempt to prevent Jin from being able to harm anyone.
Sting Scorpion literally stings Horobi with its tail stinger, and then appears as if trying to attack him head-on.
Rising Hopper simply leaps out of the Progrise Key, because Zero Zero-One is a hero.
No Lost Model is projected from the Dodo Zetsumerise Key for Kamen Rider Ikazuchi, because dodos are extinct.
However, by #10, it seems they have successfully forced full control over the animals.
One reason why Horobi and Jin removed their HumaGear Modules aside from “liberating themselves from human control” - it’s also to prevent being detected. Their rider forms lack earpieces too.
As HumaGears are essentially humans in robotic bodies, when they are forcefully converted into Magia, they are basically stripped of their humanity to become monsters against their will. It's even in the name, even, though the English translation makes it less obvious — The katakana for HumaGear can be directly transliterated as "Hyūmagia", which are reduced to Magia when they transform, losing the Hyū(man) part.
While they’re not the only example, dodos are one of the most notable examples of an ancient species going extinct through excessive hunting by humans. It’s rather appropriate that the Dodo Zetsumerise Key is used by Little Assassin, a character specifically tasked to hunt down the protagonist, a human. Dodos are also notably not very smart when faced against predators, so of course the Dodo Zetsumerise Key’s main feature is combat learning.
Normal HumaGears have blue light in their HumaGear Modules and eyes, while hijacked ones/Magia are red. The exception is Ansatsu-chan because Yua changed his lights’ color.
Horobi’s color is purple, a mix between blue and red. He retained enough control of himself but definitely not a benevolent HumaGear.
Jin’s color is pink, a light shade of red, because he’s under Horobi’s control but isn’t completely evil.
Ikazuchi’s color is crimson, because he is completely under the control of MetsubōJinrai.net.
Though still an excuse to justify him getting into new adventures every episode, personally going out to deal with customers gives Aruto a chance to learn how the business works as well as help establish himself in the corporate world.
#12 stated that Wazu was the previous assistant of Aruto’s grandfather. There’s an established naming theme for the Hiden Intelligence CEOs’ assistants: Wazu (Was), Izu (Is), and the assistant in the Kamen Rider: Reiwa the First Generation is named Will, and by #42, it was implied that their names are also the reference to different phase of Aruto himself.
He was as quirky as Wazu.
He is wholeheartedly believed in the coexistence of human and Humagear, just like Izu.
He will be sunk into villainy, just like Will.
Regarding Shining Assault Hopper. Why doesn’t it have a transformation jingle, form name, then text-to-speech and instead has two text-to-speech phrases with the form name in between? The first text-to-speech makes it clear that Shining Assault Hopper is a form that has never been done before. Keep in mind that the form is only made possible via the Assault Grip, which was created to be used in tandem with the Assault Wolf Progrise Key (which was created with data from Vulcan and Zero-One’s past battles) and made by the Ark, is being used together with Shining Hopper, which was made in similar circumstances as Assault Wolf but was created by Zea. The only reason Aruto got the idea to use the Assault Grip with Shining Hopper was because of the data Zea provided him about the Assault Grip in the first place.
The Dodo Zetsumerise Key is the first Zetsumerise Key shown to have its own standby Theme Tune when put in the ZetsumeRiser, further reinforcing that it’s unique in some way.
Some may wonder why Aruto, Isamu, or Yua don’t attempt to stop Jin from corrupting HumaGears into the next Monster of the Week. Well, considering that Jin is a HumaGear himself as well as armed-and-dangerous, it would be too risky for the heroes outside of their suits to try and fight Jin.
Unlike Isamu who starts coughing blood and barely able to stand after using Assault Wolf, Aruto doesn’t suffer a major backlash from using Shining Assault Hopper. Why? According to the wiki, Assault Wolf lacks the safeties and life support, which makes sense since Assault Wolf was designed specifically for the use of HumaGears. However, Shining Assault Hopper uses both the Assault Grip and Shining Hopper, one item made by the Ark and the other by Zea. The form is Ability Mixing at its finest, in that not only does the form combine both Shining Hopper’s incredible speed and Assault Wolf’s overwhelming brute force, it also matches the specific tasks Zea and the Ark have.
Zea creates the armors used by Zero-One, who fights to protect humans and actively works to help them co-exist with HumaGears. Naturally, Zea will do its best to help Aruto. The Ark, on the other hand, is trying to destroy humanity and focuses more on the destructive aspect like the Magia. In other words, Shining Assault Hopper has Zea keep Aruto’s body from reaching the breaking point like Assault Wolf does to Isamu, while the Ark helps Aruto by offering him a major boost in firepower.
Thouser goes all out with the king theme. Not only does he have Gold-Colored Superiority, but purple eyes, because Purple Is Powerful and associated with royalty. He was also seen in some promotional material with blue eyes, a nod to the color royal blue.
Ichigata being heroic is shown by the sounds of his Zetsumerise Key, which announces “The Sole Hero of Ju-Ju-Ju-Justice” and “Kamen Rider will fight to protect humanity” in the Hiden Zero-One Driver. The CycloneRiser, however, plays neither of them, allowing Ichigata to disguise his heroism.
It's very fitting that 001 and Ichigata's fight would end with a clash between their finishers Rising Utopia and Rocking The End; it symbolises that for Aruto to fulfil his desire to create a utopia for humans and Humagears alike, he must surpass Soreo and bring him to an end.
The form with the jingle describing increasing the power of a Rider Kick is the first one to use a boosted finisher.
Why do the Raiders look more bulky and armored than the Magia? Because there's a human inside. Unlike Magias that are 100% robot from the inside out, Raiders have to account some additional space for a human to fit in. Not to mention, the fact that there's a human inside means that the armor has to be adequate to protect them.
Both Assault Wolf and Metal Cluster Hopper Progrise Key share similarities and some differences:
Both keys were created by the Ark and are programmed to bear hatred towards humanity, but are being used against the Ark's will. While Fuwa uses Assault Wolf to focused his hatred towards MetsubouJinrai.net by his own free will and thus cannot be manipulated by Ark, Zero-One is initially forced to use MetalCluster Hopper when overwhelmed by his hatred towards Thouser [read: humanity as a whole] and vulnerable to the Ark's manipulation.
Even their color scheme reflects some of this; despite sporting a darker shade of blue, Vulcan remained heroic, dedicated to eliminating MetsubouJinrai.net once and for all while Zero-One sports a grayish-silver color representing the mixed morality of Ark's desire to destroy humanity and Aruto's efforts to prevent that from happening.
The Progrise Hopper Blade was created using the positive emotions of HumaGears as a literal counter to the Ark's malevolence. It's no surprise that as a result it can literally negate the negative emotions that the Ark pours into the ZetsumeRisers and the Zetsumerise Keys and restore native HumaGear personalities and forms.
#24 explains a lot about the series:
Where did Metsubojinrai got their Zetsumerise keys? Each Humagear has their own Progrise key that can store data. Metsubojinrai likely used discarded ones from the Humagears they stole and converted it.
Why do the Progrise keys have ability names on them? Each Humagear Progrise Key has their job name.
Why do Humagears have a particular tattoo on their body? It's for Progrise Key scanning.
How can the destroyed Humagears be remade with all the memories intact? With the data from their Progrise Keys.
In #25, there are differences of definition of Kamen Rider towards HumaGear and subtle implications of White, Gray and Black Conflict from them:
White: Aruto views Kamen Rider as a means of creating a future where HumaGear and humanity can coexist together.
Gray:
Fuwa is a full-blown Gray as he vehemently believed all HumaGear are evil after a Dark and Troubled Past occurred to him and views Kamen Rider as a mean to destroy all of them but started to have a different opinion of them after being saved by them and began acting accordingly without the reckless thinking of him.
Jin is from the villain side but he is AntiVillain that genuinely believe he will free all HumaGear from humanity and views Kamen Rider as a way to give them true freedom.
Black:
Gai's twisted view of Kamen Rider as a weapon to annihilate HumaGear by purposely instigating a war towards them in order to make profit for his own gain and to prove his ideology of Humanity Is Superior.
On the Subject of Colors:
Horobi and Gai represent opposite ends of the spectrum, HumaGear and Human respectively. Their suits when transformed are Purple with Yellow/Gold eyes and Gold with with Purple eyes. This shows their allegiance in contrast to one another. Additionally Horobi's suit uses his color motif as the undersuit with silver-black armor while Gai's has a gold and black undersuit with silver armor.
Jin and Yua's starter forms both connected to their loyalty. Jin's suit is a magenta/pink a shade of purple, showing his loyalty to Horobi, while Yua's is orange a color very similar to gold which Gai has as his represented color. Jin's second form becomes red, representing his increasingly noble intentions and brings him closer to Aruto and Isamu to complete a trio with colors representing light, while Yua's forms get increasingly darker with the gold/yellow colors becoming less dominant in each form.
Isamu and Raiden have very similar personalities and all their forms so far as of writing this have kept their main color. Isamu retains blue in all his forms while Raiden is red, they are also on the opposite side of the show's alignment spectrum much like Gai and Horobi, human and humagear respectively. The difference lies in that Isamu started full or rather predominantly human but grew as a character, while Raiden was more in the middle of the spectrum before being revealed to be a Manchurian Agent.
Bingo Bengoshi seemed to be fine the next day after gaining his data back from being a Magia through the Zetsumeriser. There is no symbol or sign of him restarting his programming from scratch. This was most likely due to not being fully hacked by the Ark despite using a Zetsumeriser, so he managed to keep his original data safe. As of now, HumaGears do not need to fear of losing their entire data because Zero-One has the Progrise Hopper Blade to repair them from the Zetsumerisers and their Magia state.
Certain characters goal are actually aligned with characters from previous series:
Aruto's goal of wanting to create a future where human and HumaGear to coexist peacefully but facing obstacles when trying to achieve that goal much like of how Haruka wishing for the same thing to his fellow Amazons.
Jin having a somewhat genuine intention (with his own way) of wanting to free HumaGear from the clutch of humanity similar to Heart that wanted to ensure his fellow Roidmude's survival.
Gai as The Man Behind the Man and Greater-Scope Villain, orchestrated multiple incidents for something grander for his own gain bear minds to Evolto playing the same role albeit to much higher destructive level.
The revelation that Gai actually made the Raid Risers and their purpose of being used by civilians makes sense on many levels, being similar to civilian versions of law enforcement and military weapons, if the Shot/Slashrisers are akin to military grade weapons. This even comes down to their design of being stripped down Shotriser belts and sharing the same undersuits as the Shotrise ones. Even the choice of using common animal ProgRise keys shares this design method.
By observing Jin's characterization before and after his revival, it makes much more sense if you think about it. Jin's Psychopathic Manchild tendencies are influenced by his connection towards the Ark through the use of the ForceRiser, which forces him to serve Metsuboujinrai.net; after his revival, he acts more mature and independent, while getting his hands on the SlashRiser can be interpreted as him slashing/severing his ties from the Ark while maintaining his loyalty to Metsuboujinrai.net.
Aruto's decision of starting a new company, Hiden Manufacturing, after his resignation as CEO of Hiden Intelligence is actually much more sense. By inheriting the title of CEO from his grandfather Kurenosuke, Aruto basically inheriting Kurenosuke's vision of wanting HumaGear and humanity to coexist together, a feat that Aruto never managed to fullfil after ZAIA's hostile takeover over Hiden Intelligence. By creating his own company while maintaining the same policy, Hiden Manufacturing basically served as a Spiritual Successor to Hiden Intelligence, continuing Kurenosuke's legacy.
The Legend Rider Progrisekeys all tie into some aspect of their users somehow.
Zero-Zero-One and OOO both have themes of reaching out towards something in their source media.
Metal Cluster Hopper and Gaim are both influenced (or will be influenced) by an inhuman force way over their heads.
Valkyrie and Drive both spin around for some of their finishers.
Horobi and Zi-O are both purple Riders whose origins are rooted in noble causes, only for something to try and twist those ideas.
Ikazuchi and Fourze are both associated with outer space.
Thouser, Build, and Decade have all had their users commit morally questionable acts in the name of the greater good (or at least what they believed was the greater good, in some cases.)
The technologies related to Zero-One being not patented to Hiden Intelligence makes sense. The transformation belts MetsubouJinrai Forceriser, A.I.M.S. Shotriser and the ZAIA Thousandriver have the group/company in their full nomenclature but the transformation belt for Zero-One is called the Hiden Zero-One Driver not the Hiden Intelligence Zero-One Driver meaning it is more aligned to the Hiden family not the company they are connected to.
The existence of Zea and Ark were actually symbolic foil to each other in many different ways:
Zea represent the Light, located far above the sky and much closer to the Sun, receiving the light from it while Ark's name is derived from Dark, located at the very bottom of the lake, utterly devoid from the light.
It can be reflected back to the respective of Progrise Key creation from them. Shining Hopper was created from the combination data of Progrise Key in Aruto's possession while Assault Wolf was created from the data of all Zetsumetsu Key.
Religious symbolism
Zea can be seen as a metaphorical God by the HumaGear, seeking guidance for what they need to do prior their creation from Zea, instead Ark is the opposite of the spectrum, a metaphorical Devil that actively corrupting the HumaGear and to a certain extent, Zero-One through its proxy, Metsuboujinrai.net or indirectly by Gai.
Purposes
Ark was created with joint cooperation of Kurenosuke Hiden and Gai Amatsu but later sabotaged by Gai himself for his agenda of mass-producing the Kamen Rider system as a weapon from Ark itself that he can sold and make profit from it while Zea was specifically created by Kurenosuke to make sure HumaGear will never be misuse and with the purpose of helping humanity going forward.
The logic behind the Ark Zero-Driver only requiring the push of a button to activate is two-fold.
The Ark designed it's Driver to be as efficient as possible by not relying on the lengthy process of readying it and a Progrise Key that most other belts require.
The Ark is going to be body hopping, a lot, meaning it's going to have to Henshin, a lot.
The way the ARK-Zero transforms seems like nonsense until you pay attention: The shapes seen coming out of the sludge are the Zetsumerisekeys' Lost Models, which then are vaporized and turned into the suit. Exactly the same way we use the extinct animals (mostly dinosaurs) which have become petroleum and then refined by humans to harness their energy (for engines or heat).
Ark pulled a Xanatos Gambit relating to the Assault Wolf Progrise Key. Seeing as Zea was able to predict the creation of the Assault Trigger, it's more than possible for Ark to predict that Naki was inside of Fuwa. If they were, then the Assault Wolf Progrise Key would link them back to Ark. If they weren't, then Ark could more easily revive them and give them the Progrise Key. Which further implies that Ark planned for Fuwa to steal the Assault Wolf Progrise Key to test its theory, knowing that if Naki wasn't inside of Fuwa it could just steal the Assault Wolf Progrise Key back.
When Naki makes a pun to demonstrate Fuwa's unexpected funnybone, they conclude with Aruto's catchphrase, "Gotta have Aruto!" This suggests that, after observing both Aruto and Isu using the catchphrase when they make puns, and in the absence of evidence to the contrary, Naki has machine-learned that one is "supposed" to utter this phrase when one makes such a pun. And so they do, perfectly deadpan. Aside from being hilarious, this also helps demonstrate that Naki is not as socialized as other HumaGears who have had greater exposure to human behavior.
Horobi's dream is to become a parent, so why it suddenly changes to Kill ALL Humans? He still holding on to his original dream and this is what motivate his current goal. After seeing how Ark harms Jin many times, he must have concludes that the only wayto protect his son from the Ark is to get rid of its source.
Rising Hopper's key evolution represents Aruto at his finest; it's a homophone pun. It can be both Realizing Hopper (realizing your dreams) or Re-rising Hopper (never giving up, rising again).
Guess the name of the final form Aruto uses. A powered-up Rising Hopper called Realizing Hopper.
The Kamen Rider Zero-One suit shows a noticeable technological progression which you can especially see in the supplementary materials.
Rising Hopper and all other basic forms use liquid armor under metal fiber mesh and metal armors of differing hardness.
Shining Hopper and Shining Assault Hopper incorporate biomechanics into their designs.
Metal Cluster Hopper is made from Nanomachines with phase transition control properties.
Zero-Two uses the technology from Metal Cluster Hopper with the addition of a built-in quantum computer.
Metal Cluster Hopper's nanomachine locust swarms are the only thing in Aruto's arsenal capable of hurting Eden. This foreshadows how later on, the similarly nanomachine-based Kamen Rider Abaddons, which are locust-themed Mooks, would assault S, and their leader would take his Eden Driver to become Kamen Rider Lucifer.
Why is the motif of Kamen Rider Lucifer a skeleton with hollowed-out details, compared to Eden's much more vibrant armor and motif of a tree? Because while S was a man whose heart was in the right place despite being severely misguided in his plans, Bell knows exactly what he is doing - albeit at the cost of any regard for ethics, morals, or even his own sentiments, essentially hollowing out all the moral agency of S's original plans.
One would think that Kamen Rider Metsuboujinrai is another case of the strong new thing being shown for its movie, until one thinks about it: The way its created implies its basically a weaponized Rider Model (the hardlight animals that become Zero-One's armor). Which in turn explains why it's so strong, as the viewer has seen the sort of damage a Rider Model can do (Mostly Rising Hopper when jumping around but also the other Models helping Aruto before becoming the armor).
It makes some sense that Yua would lose badly to Kamen Rider Metsuboujinrai even in her Justice Serval form, for a few reasons:
It's been established by Orthros Vulcan that using a Zetsumerise Key in the Shotriser creates an unstable form, so using the Serval Tiger Zetsumerise Key was already putting a lot of strain on her Shotriser.
Honey bees die after stinging humans; fittingly, Valkyrie's Justice Serval form, which is a retooled Lightning Hornet suit, was destroyed after landing one good hit on Metsuboujinrai.
Gai looking significantly younger than his age of 45 can partially be justified by the fact that he's almost always toting an umbrella to keep the sun off him when he's outside (and spends the majority of his working time indoors). Although there are many other factors in skin aging, one of them is exposure to sunlight throughout ones life.
The Magia themselves are walking Fridge Horror. HumaGears are intended to be modeled on humans and are for the most part human-like. The first three episodes are bad enough, but when a HumaGear becomes a Magia from someone who is a authority figure for children such as school teachers, coaches like Kobe, a babysitter, or tour guides like Anna, not only would children be scarred physically if they survived, but mentally as well; the fact that the Magia suddenly betrayed their wards and attacked them would have unfortunate consequences. This might cause children to distrust both HumaGears and human adults alike.
Adding to this is the fact that the requirement to use a ZetsumeRiser is for a HumaGear to Grow Beyond Their Programming, e.g. start to develop a personality and thoughts of their own, or in other words, start having a soul, which is full of horrifying implications that just as they are starting to really feel, only for some lunatic to wipe it away. It’s also implied that the Zetsumerise Keys hold of this data to be fed to the Ark. Somehow they made the robot version of Soul Eating.
Some HumaGears like Seine are modeled after real people and there is a law against making HumaGears to resemble people without their permission. Not only does it make it so they can’t move on from their loved one’s passing, it can also make them experience the pain of losing them again if an accident happened. Or worse, they’re turned into a Magia…
Notably, despite this, Aruto’s father is explicitly shown to have a different style of HumaGear Modules, so he’s likely to be a prototype made at the time before the law was fully implemented or given permission if it was after, unlike Seine. Furthermore, the original Seine died 3 years ago, and it’s implied that the HumaGear Seine was only ordered somewhat recently, so she couldn’t have given any permission, resulting in Isamu insisting that Seine has to be taken away.
#6 revealed that Jin is a HumaGear created by Horobi. And that much like any of the others, he can be reprogrammed, as when Jin begins to show signs of doubt, Horobi slaps the MetsubōJinrai ForceRiser on him, returning him to his “typical” self. Where’s the Fridge Horror in this? Well, how do we know this is the first time that Horobi has done this to Jin?
What A.I.M.S. is implied to do with illegal HumaGears they arrest is summarily destroy the HumaGears without prejudice.
To matters worse is that while HumaGear replacements can be made with their memories and personality intact, A.I.M.S. would not care, seeing them merely as rogue machines. So they not only get destroyed, but the A.I. inhabiting it also dies for real.
One HumaGear gets “arrested” by A.I.M.S. and merely analyzed, then released to do whatever it was supposed to, even though its purpose is to assassinate someone. However, the whole thing appears to be Yua’s personal operation, which has its own Fridge Horror implications…
In #9, Jun Fukuzoe decides that the rampage at the hospital must be stopped as MetsubōJinrai.net hacks more HumaGears, and thus insists his President shut all the HumaGears in the hospital down at once. It doesn’t last for long, but imagine how many people were left without care during the incident.
Aruto’s hesitance to attack or let anyone attack the Crushing Buffalo Raider in #18 makes a horrifying amount of sense when one takes into account the fact that most all of the riders’ finishing moves tear HumaGears to pieces. Aruto’s panicked responses show that he’s afraid of what they could do to a far less durable human.
With the revelation of the ShotRiser are required to have a special chip in order to operate said Riser, it's a beg of questions. When Fuwa was using the Assault Wolf Progrise Key for the first time, does that mean he has been hacked all the time and if that's true, what he has been doing during his unconscious time?
He was being used as Naki's vessel and working for Gai without being aware of it. This brings what was normally an Idiot Ball moment into a darker light... When he presented the evidence of Daiki's ZAIA Spec right in Gai's face, allowing him to destroy the only means he had of exposing his crimes, was that really a mistake on Fuwa's part... or Naki just bringing the evidence to Gai for him to dispose of?
Also Gai's recall of HumaGears has some implications. Is Gai planning to reprogram all the recalled HumaGears instead of scrapping them, making them loyal to Gai himself? Perhaps make it easier for them to become Magia?
Explained later on: it was part of his plan to try to stop Ark, by limiting how many vessels it could have. Didn't work.
Gai has every Progrisekey save for Hopping Kangaroo, Assault Wolf, Metal Cluster Hopper, and Burning Falcon either in his possession or on file thanks to the Thousand Jacker, meaning he could theoretically have an army of Raiders with various powers and abilities.
The Ark AI, as terrifying as it is, was never truly completed. It was suposed hold the singularity data of all Zetsumerise Keys and those of MetsubouJinrai.net. But Jin's ressurection as Next-Gen Humagear meant that Azu couldn't get his Singularity data. So in-series the Ark (as Ark-Zero)was operating at at least 75% of its Intended capablities. How scary is that? a completed Ark could have foreseen the betrayal of the members of Metsuboujinrai from the begining and rigged Breaking Mammoth to self-destruct with Raiden inside, securing the Satellite Zea hardware from where it could have destroyed humankind with impunity.
It's worse than that because Ark will exist for as long as malice exists within humamns or HumaGears. Even destroying a vessel will just delay its inevitable return.
In #40, Aruto asks Izu to run "billions of simulations" to awaken the power to create the Zero-Two Driver. This may mean she had to watch Aruto die billions of times. Small wonder she started crying!
Izu establishes that she had established a new company for Aruto to be the president of after Gai buys out Hiden Intelligence... Thing is, it's established that Humagears do not get paid any money, which means that she had to have stolen the money from either Aruto or Hiden Intelligence.
Isamu forcing open his Progrise Key to transform implies two possibilities of how his equipment works:
He would have gotten the Key authorized to open anyway if he inserted it into the A.I.M.S. ShotRiser first (like how Yua does it), but he is too hot-blooded of an idiot to realize it. (This is confirmed in the narration of the Shooting Special clip show, as Yua scolds Isamu for not doing it right.)
Forcing it open forces the Key to shift into “authorized” mode and activates it for full use, much like how the MetsubōJinrai ForceRiser force-activates Progrise Keys. Also, now being able to easily force it open with one hand implies he broke the lock on it.
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