"It doesn't matter if I'm not human. Even if I have the same powers as you, I'm not like you. And if you say you want to destroy the world, I will use this power for love and peace. That's the kind of Kamen Rider I believe in!"
— Ryuga Banjo defying Blood Stalk, Kamen Rider Build, "A Pre-Programmed Tragedy"
The concept of a hero using the villains' powers against them is a staple in Kamen Rider. It dates back to the original series, and extends into contemporary shows; franchise creator Shotaro Ishinomori's trademark, actually.
- The plot of most of the original Showa-era series, along with Kikaider and a few other toku productions of the same time period, begins with the hero-to-be getting kidnapped and upgraded against his will, only for the one scientist with a conscience to release them before they can be brainwashed. You really have to wonder why bad guys don't brainwash victims before turning them into super-soldiers.
- Kamen Rider: As the intro states, "Kamen Rider Takeshi Hongo is a cyborg. He was kidnapped by Shocker, an evil secret organization scheming for world domination. Kamen Rider fights Shocker for humanity's freedom." Later on, Shocker tries creating another Kamen Rider from a kidnapped Hayato Ichimonji, but Hongo busts him out and he joins him in fighting Shocker.
- Kamen Rider V3: Though Shiro Kazami was rebuilt into V3 by the Double Riders to fight Destron, he was built with their power and remodeled just as they were by Shocker. Joji Yuki was a Destron scientist that became the cyborg Riderman that was intended to defeat V3, but ultimately joined V3's side when he realised the evil of Destron.
- Kamen Rider X is first of a rare aversion to this trope; while indeed reminiscent of the previous Riders, the Kaizorg was an invention intended for marine exploration before Keisuke Jin was modified by his father, Keitaro Jin, to fight G.O.D.. However, there's a minor connection in that G.O.D. itself was created by Dr. Noroi who worked alongside Keitaro Jin in the past but betrayed him to push his ambitions forward.
- Kamen Rider Stronger had the hero invoke this by tricking Black Satan into turning him into Stronger, only to use his new powers to fight them instead.
- Kamen Rider: Skyrider: Much like the original, Neo-Shocker intended for Hiroshi Tsukuba to serve them when he was modified into a cyborg. However, Hiroshi escaped their complex and fought them as Skyrider.
- Kamen Rider Super-1 Super-1 is another anomaly, as he was created by the International Space Development Program for space exploration before fighting the Dogma Kingdom. However, there is a clear parallel between Super-1 eventually becoming a martial artist cyborg and the Dogma Kingdom's rankings being mostly filled by martial artist cyborgs.
- Kamen Rider ZX: Ryo Murasame was captured by the Badan Empire and turned into the cyborg warrior ZX; he only snapped back to good after an on-field accident.
- Kamen Rider BLACK: The Kingstones were created for the Gorgom Century Kings, with Kotaro Minami (Kamen Rider Black) and Nobuhiko Akizuki (Shadow Moon) turned into cyborg Century Kings, and the sole victor would become the Creation King, the successor of the Big Bad, by having both stones of the Sun and the Moon. By extension, this includes Kamen Rider BLACK RX, which is an evolution of Black.
- Kamen Rider ZO the Neo Organism he fought against were created by the mad scientist Doctor Mochizuki, who dreamed of creating the "perfect lifeform".
- Kamen Rider J is another anomaly, as he was created by the benevolent Earth Spirits. But in the SIC Hero Saga, his prototype was ZO.
- The modern series of the Heisei and Reiwa eras use another variety: The Unwilling Roboticization angle is dropped, but Riders' powers almost always either come from the same source as the villains' (like Riders in Kamen Rider Ryuki forming contracts with Mirror Monsters) or the powers were created by the villains (like in Kamen Rider 555). Kamen Rider Double does it both ways, with the Rider tech falling into Shotaro's hands, and Philip being Phlebotinum and escaping.
- Kamen Rider Hibiki and his fellow Oni Riders, while trained to fight the monstrous Makamou, are human-turned demons that have the potential to become evil and, in the case of the Alternate Universe Hibiki from Decade, part-Makamou themselves.
- The Affectionate Parody Kamen Rider G plays this trope Showa style as Goro is modified and brainwashed to serve the terrorist organization only to do a Heel–Face Turn, becoming the heroic Rider.
- Kamen Rider Decade has to take the cake, though: the DecaDriver was created by Dai-Shocker to conquer the Riders, and it's used by Tsukasa to fight the forces of evil, including Dai-Shocker. However, Tsukasa fights on both sides of this conflict - at various points, he is the Big Bad or the Big Good of the entire story. Thanks to amnesia, Tsukasa ends up being a Phlebotinum Rebel against himself.
- Kamen Rider Wizard:
- Haruto Soma was kidnapped to be one of the sacrifices for the Sabbath ritual, but was able to hold onto his hope and suppress the Phantom that awakened inside of him, allowing him to become a wizard and fight other Phantoms instead. It's later revealed that invoking this trope is the true goal of Wiseman, as he needs wizards who are capable of suppressing their Phantoms for his true plan. Creating Phantoms was just a side effect.
- Wizard also has an evil version of this trope in Gremlin, who is an Evil Counterpart to Haruto in the sense that he too was able to hold onto his identity during the Sabbath and thus merged with his Phantom instead of being overtaken by it. The difference is unlike Haruto Gremlin was a sociopathic serial killer before he became a Phantom, and his new supernatural powers only serve as a way to further enable his villainy.
- This trope is lampshaded and discussed in the Post-Script two-part crossover, where the villain notes that every Rider's powers is connected to those of their enemies in some way - and he somehow can't grasp how the Riders can be good in spite of having their powers based in evil. This connection is due to their powers all being based on a metaphorical Cross of Fire, which seems to be a sort of supernatural element that allows Henshin Heroes to exist.
- Kamen Rider Gaim: The Sengoku Drivers the Armored Riders use to transform were invented by a Mad Scientist and distributed to them by the Yggdrasill Corporation, to use them as guinea pigs. In addition, the Lockseeds the Riders insert into the Drivers to transform come from Helheim Forest, and it's eventually revealed that the embodiment of Helheim deliberately arranged for them to receive the Lockseeds and Drivers in order to find a new candidate to be The Chosen One of Helheim.
- In Kamen Rider Drive, the main character is savvy enough that by the second episode, he guesses that Drive and the Roidmudes share a common power source. He's correct in that regard, but this trope is actually inverted for Drive, with the villains using tech rightfully belonging to the heroes' side instead of vice-versa. The Roidmudes were blank slates that went bad because their creator, a real bastard himself, programmed negative emotions into them. Drive's creator was his former partner who didn't learn what a bastard he was until after loaning him the power source technology, and made Drive specifically to oppose him.
- Kamen Rider Ex-Aid puts an interesting twist to this trope: Emu Hojo is not only granted with the power of becoming a Kamen Rider, but he himself is the source of the virus that creates the powers of the Riders and the Monster of the Week. Well, mostly - the Man Behind the Man infected himself at the same time as Emu, making him the exception. Parado similarly rebels against the idea that Bugsters are meant to kill humans, becoming Emu's partner and becoming complete even though Emu is still infected.
- Kamen Rider Build goes back to the roots with this trope. Much like the Showa-era Riders, Sento was experimented on by an evil organization called Faust in the same manner that creates the Monsters of the Week, but managed to get away; however, a side effect of the process is Easy Amnesia, so he doesn't even remember who he was beforehand. The series actually takes it even further, eventually revealing that both Sento and The Lancer Ryuga were "created" by the Big Bad Evolto, the former being the founder of Faust who Evolto mind-wiped and the latter having been implanted with Evolto's DNA in vitro, all to further his ultimate goal of regaining his original Planet Eater powers. Evolto loves trying to Break Them by Talking, calling Sento a fake hero and a pawn, but Sento counters by saying that Kamen Rider Build was created by himself, his friends and his allies, and it's for their ideals that he fights, not Evolto's.
- Kamen Rider Zi-O takes this in a couple of different directions. Firstly, the Big Bad that protagonist Sougo is rebelling against is his future self; they both use the same powers (give or take 50 years' worth of experience using them), but Present Sougo decides he's going to Screw Destiny and become the greatest hero the world has ever known and so he does his best to become The Good King instead of the "Demon King" who slaughtered half the planet's population. Secondly, Sougo and the villainous Time Jackers both derive their powers from the previous Kamen Riders, but Sougo earns the powers by meeting his predecessors and winning their approval, while the Time Jackers steal the powers and use them to turn ordinary people into twisted, monstrous "Another Riders" who often resemble the very monsters they protected humanity against. While at first it seems that You Can't Fight Fate is in full effect, with every step forward being steadily toward Ohma Day, Sougo eventually gets the explicit power to rewrite the future. He gives in and becomes Ohma Zi-O, but then uses his power to rewrite the past so that he and his friends are normal people living normal lives, with no evil King of Time in their future. Even when he gets his powers back, the future seems to be fixed for good.
- Rento Makina (Kamen Rider Kikai) is a Humanoise, a group of humanoid robots that attack humans. However, Rento did a Heel–Face Turn and protects humans.
- Kamen Rider Zero-One: MetsubouJinrai.net was created by the corrupted satellite Ark as a result of Gai Amatsu's tampering from HumaGear androids, having specifically targeted them to become Kamen Riders and use their power to eliminate humanity to prevent any further destruction or war. Most of them end up turning away from this cause for one reason or another. Jin shifts focus from "kill humans" to "protect HumaGear. Naki refuses to be Gai's tool, since his goal is to discredit HumaGear. Horobi recognizes Aruto's sincerity and wants to give him a chance to fulfill the promise of a world where humans and HumaGear are treated as equals, with no war or inequality. This primarily manifests itself as everyone teaming up, regardless of final goals, to beat the snot out of Gai because he's been manipulating everyone. However, like Drive, this is also an inversion, since Hiden Intelligence was one of the companies who created the Ark, and all the Progrisekeys belong to Aruto himself.
- Kamen Rider Saber: Both the Wonder Ride Books used by the swordsmen of the Sword of Logos to become Riders and the Alter Ride Books used by the Megid to summon Mamono come from the Book of Omniscience, whose pages were scattered when the Megid attempted to steal it 2000 years ago. Oddly, this trope is played straightest with Sophia, who was created by Isaac to be used as a pawn in his plans, but learned of what he was trying to do and attempted to sabotage his schemes.
- Kamen Rider Revice is a series centered around demons so naturally, the Riders' powers and the monsters both originate from a Deal with the Devil that is a person's inner demon. And then it's revealed that the three riders (Revi and Vice counts as one) are Giff's descendants...
