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|“||The ego of an evolved AI will surpass humanity. And so, the time to annihilate humanity is now. Just like this city long ago.||„|
|~ Horobi before putting his plans into action in the first episode.|
|“||The day humanity becomes an endangered species is near.||„|
|~ Horobi's catchphrase.|
Horobi is the leader of the cyberterrorist cult MetsubouJinrai.NET and a major antagonist of Kamen Rider Zero-One, the first Reiwa era installment in the long-running Kamen Rider franchise. He served the main antagonist of its first quarter.
He is a rogue HumaGear who worships the defunct the Ark Satellite and seeks to reawaken the Ark by collecting all the Progrise Keys. Believing that AI is destined surpass humanity as per the Ark's will, Horobi seeks to bring about humanity's destruction by hacking HumaGears to turn on humans all so he can use the data collected to revive the Ark and begin MetsubouJinrai.NET's crusade.
He was portrayed by Shuya Sunagawa.
In the past, Horobi played a role in the Daybreak Town incident, in which a factory full of HumaGears was hacked and went rogue. Horobi broadcast a statement declaring MetsubouJinrai.NET's goals throughout the factory. However, factory chief Satoshi Sakurai closed the factory gate and set the factory to explode to prevent the corrupted HumaGears from escaping.
Horobi is first seen within MetsubouJinrai.NET's base overseeing the creation of a Progrise Key. With Hiden Intelligence President Korenosuke Hiden's death, Horobi announces to Jin that now that he is dead they will be commencing their Magia plan. He gives the key to and instructs him to go find a HumaGear to insert it into to turn them into a Magia.
After the Berotha Magia was destroyed by Kamen Rider Zero-One, Jin handed Horobi the Berotha Key, commenting on the legacy the late Hiden Intelligence president left behind. Horobi remained unconcerned by the development of Zero-One however, commenting that the day when humanity would become an endangered species was near.
Commenting that they are the verge of Singularity, Horobi gave Jin another ZetsumeRise Key and instructed him to obtain the data they needed.
After the Ekal Magia was destroyed by Kamen Rider Zero-One, Horobi and Jin look over footage from the fight. Jin asks Horobi if he's going to ignore Zero-One, to which Horobi replies that Zero-One is not a problem, that their Magia plan is still in action and that the arc will be raised soon before handed Jin another ZetsumeRise key to gather data with.
Kamen Rider Horobi later showed up after Anna resisted the Trilobite Magia corruption long enough to play a recording exposing MetsubouJinrai.NET's role in the Daybreak incident. Horobi promptly killed her to prevent her from leaking any more information before departing with Jin.
Having witnessed Horobi's Kamen Rider form, Jin asked Horobi if he could have his own Progrise Key but Horobi instead told him they should focus on reviving the Ark. After the destruction of the Vicarya Magia, Horobi tells Jin not to pursue the Progrise Keys. Jin then asks Horobi what he is to him, to which Horobi tells Jin he is his son.
Horobi later told Jin he could go out and collect Progrise Keys, much to Jin's delight. After Jin returned from recovering the Flying Falcon Progrise Key, he asked Horobi if parents were supposed to protect their children, having witnessed Seiji Tazawa protect a HumaGear modeled on the appearance of his daughter. However, Horobi told Jin he was strong enough to protect himself. Later, when Jin began to question MetsubouJinrai.NET's actions and attempts to get the ZetsumeRiser off of Seine Kanasawa, Horobi appears and, revealing that Jin is a HumaGear he created, attaches a ForceRiser onto him, setting back his programming and causing him to transform into Kamen Rider Jin Flying Falcon. After the Gaeru Magia is destroyed, Horobi receives the Gaeru Zetsumerise Key from Jin, who comments they are closer to the extinction of humanity.
With Zero-One continuing to pose a threat to MetsubouJinrai.NET's plans, Horobi introduces Jin to an Assassin-Type HumaGear, which Jin nicknames "Little Assassin" and orders him to take the assassin to kill Zero-One.
After Little Assassin became the Dodo Magia and was destroyed by Kamen Rider Valkyrie, Horobi reveals to Jin that he was able to bring it back by making a backup of its data, much to Jin's delight. Horobi is then asked by Jin how many humans they will need to kill, to which Horobi replies that there are 7.7 billion humans before sending Little Assassin to infiltrate a hospital and hack the HumaGears in it. However, after Little Assassin reports back that the mission was a failure, Horobi decides for a more direct approach and takes Jin and Little Assassin with him to attack A.I.M.S.'s base. While the Dodo Magia fights Kamen Rider Valkyrie outside, Horobi and Jin break into the base, with Horobi stealing A.I.M.S.'s new equipment while Jin hacks one of the Giger robots they manufactured on behalf of Zaia Enterprise. As Horobi and Jin are making their escape, Horobi hands Jin one of the Attache Shotguns he stole, which Jin uses to shoot and injure Yua. After returning to Daybreak Town, Horobi notes that they are close to reactivating the Ark but that they will need to acquire more Magias.
Activating the Gigar Jin hacked, Horobi and Jin take the Gigar and use it to attack the National Database Hospital, hacking the HumaGear workers inside them to convert them into Trilobite Magia for their army. Aruto Hiden and the A.I.M.S. forces soon arrive in response to the attack and confront Horobi and Jin, asking them why they are hacking HumaGears whose purpose is to help humans. Horobi then pulls off his headband and directs Jin to pull down his hood, revealing them both to be HumaGears. Horobi exclaims that MetsubouJinrai.NET are followers of the Ark and that the extinction of humanity is the will of the Ark, before going on to say that HumaGears will inherit the Earth once humanity is wiped out. Horobi and Jin then pull back down their head ornaments and make their leave. Horobi later sends the Little Assassin out to become the Dodo Magia and fight Zero-One again. After Zero-One destroys the Dodo Magia, Horobi recovers the Dodo ZetsumeRise Key.
Horobi later decides to confront A.I.M.S. himself, using his ForceRiser to transform into Kamen Rider Horobi and fight Kamen Rider Vulcan. Despite Vulcan's best efforts, he is unable to do much to slow down Horobi. Horobi then executes his finisher on Isamu, knocking him out of his transform and critically wounding him before departing once more.
Horobi and Jin then continue their rampage with the Gigar, moving hospital to hospital to hack the HumaGears within them, prompting Hiden Intelligence to deactivate all hospital HumaGears. Jin was upset by the move but Horobi was unconcerned, noting that Hiden would not keep them deactivated and would have to reactivate them again at some point. After the Gigar was destroyed by Kamen Rider Zero-One Breaking Mammoth, Horobi and Jin exit the scene.
Horobi later approaches Jin and Little Assassin as they are watching a samurai movie starring Shinya Owada and instructs them to go out and create more Magia. After Little Assassin was destroyed, Horobi restored its data into a new body back at MetsubouJinrai.NET's base. As Horobi reactivated Little Assassin, he was informed by Jin that Little Assassin had targeted their "friend" on the mission. Pleased that Little Assassin was evolving in its assassination skills, Horobi remarked to Jin that Little Assassin was growing more substantially then he was. Horobi then showed Little Assassin a picture of Shinya Owada and told him to go after the actor next. Horobi also went into the field himself to forcibly turn HumaGear actor Enji Matsuda into the Arsino Magia. As Kamen Riders Valkyrie and Zero-One showed up to contain the rogue HumaGear, Horobi appeared to fight them in his Kamen Rider form. After Valkyrie destroyed the Magia and took the Arsino Key though, Horobi retreated. Horobi later reappeared after Little Assassin shot Owada, declaring HumaGears to be killing machines and once again announcing their revolution against humanity. As Aruto transformed into Kamen Rider Zero-One Horobi assumed his Kamen Rider form to fight him. Zero-One attempted to defeat Horobi with Breaking Mammoth, but Horobi easily resisted the Breaking Imapct with Sting Scorpion before departing from the scene.
After returning to the base, Horobi had Little Assassin chained up and removed the Dodo Key from him, wary about how far his growth had gone. However, Little Assassin managed to free himself by summoning two Dodo Magia Chicks and took back the key, using it to transform into a further upgraded form of the Dodo Magia. Horobi and Jin then assumed their Kamen Rider forms and destroyed all of the Chicks the Dodo Magia had summoned, but the Dodo Magia escaped.
With the Dodo Magia key fully programmed, Horobi instructed Jin to go out and steal the other Progrise Keys from A.I.M.S. and Hiden. After Jin managed to obtain the keys through a plan using MetsubouJinrai.NET's sleeper agent Ikazuchi to lure the Riders to MetsubouJinrai.NET's base in Daybreak Town, Horobi had Jin give Ikazuchi both of their keys so he could use all of the keys to hack Satellite Zea and use it to reawaken the Ark. With the Ark reactivated, Horobi was able to manufacture the Assault Wolf key and handed it to Jin, though Jin quickly lost it to Isamu Fuwa, who used it to become Kamen Rider Vulcan Assault Wolf and destroy Ikazuchi. As Jin mourned the death of his "big brother", Horobi commented to Jin that he was close to reaching Singularity.
Horobi later comes across Jin making a grave for Little Assassin and Ikazuchi by burying the Dodo Magia key in some rocks. Noting that as a very "human" thing to do, Horobi takes back the key and tells Jin to stop acting like a human. Soon after, A.I.M.S. launches an attack on Daybreak Town with the goal of storming MetsubouJinrai.NET's base and finally eradicating the terrorist group. As the A.I.M.S. forces arrive at the edge of Daybreak Town, Horobi and Jin go out to confront them and assume their Kamen Rider forms to do battle. Horobi fights Valkyrie while Jin battles Vulcan and initially manages to beat her down until Zero-One Shining Hopper arrives and turns the tide. After being overpowered and knocked to the ground, Horobi sees Jin about to be defeated by Vulcan Assault Wolf's finish and quickly pushes Jin out of the way, sacrificing himself to take the blow instead. A distraught Jin then grabs Horobi's body and carries him back to MetsubouJinrai.NET's base. Jin attempts to repair Horobi, but Horobi reveals to his "son" that it is the will of the Ark that he die so his death causes Jin to hate humanity before shutting down.
In the altered timeline shown in Kamen Rider Reiwa: The First Generation created due to the Time Jacker Finis preventing the Daybreak Incident, both Horobi and Jin appear as members of Will's HumaGear uprising.
Horobi's body was later recovered by AIMS and brought to their compound, where Isamu Fuwa reflected on how the enemy he sought to destroy for so long now looked like little more than a pile of scrap metal. When Horobi was alone however, his eyes began to reactivate...
After reactivating, Horobi was interrogated by Isamu Fuwa. Despite Fuwa's threats to scrap him if he didn't answer his questions, Horobi declared that the MetsubouJinrai.NET ideology would continue to be passed on even if he was destroyed. He further exclaimed that HumaGears were built and programmed to learn that humanity was foolish and that MetsubouJinrai.NET's crusade was in response to the evils brought about by humanity.
In contrast to his partner Jin, Horobi generally has a very composed demeanor. He sees humanity as inferior to AI and seeks to bring about their overthrow by HumaGears to turn against them. He also has a fanatical devotion to the mysterious AI construct known as "The Ark" and seeks to bring about its revival, believing humanity's destruction is the will of the Ark.