List of Kamen Rider Ryuki characters

Shinji Kido (城戸 真司, Kido Shinji) is a 23-year-old good-hearted, friendly, simple, and naive idealist who works at the ORE Journal as a journalist trainee. He investigates a man named Koichi Sakakibara, whom disappeared, and finds a card deck in Koichi's apartment and eventually encounters a dragon named Dragreder which attacked him but was then mysteriously repelled. Later that day, he falls into a car window and ends up being dragged to the Mirror World. He was attacked by Dispider then was saved by Ren Akiyama, Kamen Rider Knight. Shinji was told to stay out of the Rider conflict, but he decides to become a Kamen Rider to prevent Mirror World monsters from devouring humans and eventually, he contracts Dragreder and becomes Kamen Rider Ryuki to protect people's lives and stop the Rider War. With the Survive Rekka (サバイブ烈火, Sabaibu Rekka, Survive Raging Fire) card, the card he received from Shiro Kanzaki, he eventually gains the ability to transform into Kamen Rider Ryuki Survive (仮面ライダー龍騎サバイブ, Kamen Raidā Ryūki Sabaibu).[1][2][3][4] Although he died protecting civilians from a pack of Raydragoons, Yui's death convinces Shiro to negate the Rider War and avert all of the deaths that took place; with most of the former participants, including himself, living normal lives afterwards.

In Kamen Rider Zi-O and its Rider Time: Kamen Rider Ryuki side story, Shinji developed a fear of mirrors when his grudge towards the ORE Journal's clients for not supporting his former workplace created Mirror Shinji and attempted to end his life before Kamen Rider Zi-O helped him accepts his other self and finally move on. Soon after, Shinji ends up being drafted into a new Rider War while slowly regaining his memories as he wins the Rider War and fights Another Ryuki before leaving him to Zi-O and Geiz while honoring Ren's final request to check on Eri.

Shinji Kido is portrayed by Takamasa Suga (須賀 貴匡, Suga Takamasa).

Ren Akiyama (秋山 蓮, Akiyama Ren) is a 24-year-old cold loner who fights constantly and is frequently unemployed. He received his Rider deck before the start of the series. He accepted Kanzaki's offer to join the Rider war to give his fiancé, Eri Ogawa, a full recovery as she was in a mysterious coma ever since an encounter with Darkwing. Ren later contracted with Darkwing and became Kamen Rider Knight (仮面ライダーナイト, Kamen Raidā Naito). With the Survive Shippu (サバイブ疾風, Saibabu Shippū, Survive Hurricane) card, he eventually gains the ability to transform into Kamen Rider Knight Survive (仮面ライダーナイトサバイブ, Kamen Raidā Naito Sabaibu).[1][2][4]

In Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story, Ren ends up being drafted into a new Rider War while slowly regaining his memories before dying defeating Takeshi Asakura, asking Shinji to check on Eri.

Ren Akiyama is portrayed by Satoshi Matsuda (松田 悟志, Matsuda Satoshi).

Kamen Rider Zolda (仮面ライダーゾルダ, Kamen Raidā Zoruda) is a Kamen Rider specialized in long-range combat with Magnugiga as their Contract Monster.

Shuichi Kitaoka (北岡 秀一, Kitaoka Shūichi) is a 30-year-old self-proclaimed "super-lawyer" who tends to only help someone if he has something to gain. Because he has a terminal case of cancer and has been given only a few months to live, he accepted Kanzaki's offer to join the Rider War. His prize is to be immortal so that he could continue his extravagant lifestyle. Because of his illness, he suffers from frequent dizzy spells and fainting. He fights as the first Kamen Rider Zolda, though he eventually had Goro take his place during the final day of the Rider War. Though he died, his death was temporary averted once the Rider War ran its course.[1][2][3][4] In Kamen Rider Ryuki: Episode Final, Shuichi forfeited due to his health. In the 13 Riders special, Shuichi is among the Kamen Riders that attack Shinji. In 13 Riders, Shuichi visited Takeshi in prison noting that he knows about his status as a Kamen Rider. He is among the Kamen Riders that attack Shinji and Ren.

During Kamen Rider × Super Sentai: Ultra Super Hero Taisen, the Game World's Shuichi was chosen by the said world's Masato Jin/Beet Buster into Emu Hojo/Kamen Rider Ex-Aid's team, in term of his contract service. Shuichi temporarily assumes the form of the green-colored Midorider (ミドライダー, Midoraidā), a hybrid of Green Ranger and the Double Riders, once he and his team prevail in the Game World's Ultra Super Hero Taisen tournament. In this form, he rides the Gokaigers' Gokai Galleon against the Xevious fleet. By the events of Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki storyline, Shuichi passed on with Goro as succeeding him as Zolda.

Shuichi Kitaoka is portrayed by Ryohei (涼平, Ryōhei).

Goro Yura (由良 吾郎, Yura Gorō) is Shuichi's 25-year-old loyal secretary who is highly skilled with household work and hand-to-hand combat. He is also aware of Shuichi's activities as a Rider and helps as much as he can. Goro was once Shuichi's client. Because of that, Shuichi's condition was not diagnosed in time. Feeling in debt, Goro decided to be his loyal secretary and bodyguard forever. He would later serve as the second Zolda, taking over for a dying Shuichi as he died fighting Takeshi before being brought back to life when the Rider War's events were averted.

In Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story, Goro is being drafted into a new Rider War and feigns having no memory of the previous Rider War while posing as Takeshi's secretary until an opportunity to kill him presents itself. Goro gets his chance, but dies inflicting the death wound on Takeshi.

Goro Yura is portrayed by Tomohisa Yuge (弓削 智久, Yuge Tomohisa).

Takeshi Asakura (浅倉 威, Asakura Takeshi) is a 25-year-old sadistic and bad-tempered criminal who murdered his entire family during childhood, gaining a reputation for having a love to fight and kill in his random fits of rage. As a result of his sadistic nature, prior to becoming a Rider, Takeshi was personally responsible for both ending the piano career of Miyuki Tezuka's friend Yuichi Saito and the murder of Miho Kirishima's older sister. His arrogant personality resulted with his defense attorney Shuichi Kitaoka refusing to represent him and leaving him to rot in jail. Because he was in prison and could not feed his destructive nature, Takeshi gladly accepted Shiro's offer to join the Rider War and forms a pact with Venosnaker, using his newfound powers as Kamen Rider Ouja (仮面ライダー王蛇, Kamen Raidā Ōja) to break out of jail and get his revenge on Shuichi, learning of his identity as a Kamen Rider.

Over the series, thanks to Ren helping him fake his death to ensure no interference, Ouja manages to kill off both Gai and Raia, taking their contract monsters as his own. But once the police learn he is still alive, Takeshi was once more wanted as he attempts to settle things with Shuichi. By the end of the series, Takeshi finally has his showdown with Zolda and defeats him. However, Takeshi finds out seconds later that "Zolda" was actually Goro, resulting with him in utter disarray of being denied the right to kill the man he hated the most as he is gunned down by the police before his demise was averted. When time is reset, he was last seen maintaining a low profile. In the movie's alternate ending due to Ryuga's intervention during his fight with Femme in the Mirror World, Takeshi ends up being dissolved into nothingness after Femme destroys his deck.[1][2][3] In the 13 Riders special, Takeshi is among the Kamen Riders that attack Shinji after Venosnaker springs him from prison.

In Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story, Takeshi is being drafted into a new Rider War and is the only one to retain his memories of the previous Rider War. After being fatally wounded by Goro, Takeshi dies after killing Ren.

Takeshi Asakura is portrayed by Takashi Hagino (萩野 崇, Hagino Takashi).

Kamen Rider Odin (仮面ライダーオーディン, Kamen Raidā Ōdin) is a mysterious golden entity who fights with his contract monster Goldphoenix. Being a sentient Rider deck that Shiro Kanzaki created, provided with host bodies to control, Odin serves as the man's representative in the Rider War while watching over Yui. His powers include teleportation and his ability to rewind time to the beginning of the Rider War via his Time Vent card. Odin possesses incredible strength, the ability to teleport short distances, and the ability to shoot a gust of golden feathers. Odin also possesses powerful cards, namely the Time Vent card that allows him to reverse time to the beginning of the Rider War and the Survive Mugen (サバイブ無限, Saibabu Mugen, Survive Infinite) card which makes him invincible when used with the Survive Shippu and Survive Rekka cards. Throughout the Rider War, Odin makes brief appearances and fights the other Kamen Riders before he and Knight Survive are left. But after a climactic battle, Odin disappears after Kanzaki sees the pointlessness of the Rider War as it was rendered null and void upon Yui's death.[1][4] In the 13 Riders special, Kamen Rider Odin is among the Kamen Riders that attack Shinji.

During the events of Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story, Odin resurfaces and turns Tatsuya Kanō into Another Ryuki to establish a new Rider War for his agenda of resurrecting Yui. Odin battles Kamen Riders Zi-O and Geiz after they defeated his Another Rider, destroyed for good after the Time Riders used the Ryuki and Knight Ride Watches to negate his Survive card combo.

Kamen Rider Odin is voiced by Tsuyoshi Koyama (小山 剛志, Koyama Tsuyoshi) who also provides the voice of the 13 Rider's Visors.

Masashi Sudo (須藤 雅史, Sudō Masashi) is a 28-year-old corrupt police officer using his job to cover up his illegal activities disposing of any witnesses to his acts. He had a partner, the older Tomoyuki Kaga (加賀 友之, Kaga Tomoyuki) who owned the antique and collection shop, until the older man's demand for a bigger cut in the profit made Sudo kill him, plastering him into the wall of his own shop seconds before Kanzaki appeared and offered him a Rider deck explaining the terms of accepting it. Sudo took it gladly and made his contract with the Mirror World monster Volcancer, becoming Kamen Rider Scissors (仮面ライダーシザース, Kamen Raidā Shizāzu) and playing a part in the disappearances as he feeds his victims to Volcancer. He and Kamen Rider Knight confronted each other once prior to the series, neither aware of each other's identity.

Reiko's investigating of Kaga's shop after finding a link between it and some of the missing people made her a target of Sudo as he manages to hospitalize her. Shinji is then sent to continue in her place, confronting Scissors in the Mirror World before Ren saves him. Though both believed Scissors to be Kaga, Shinji acts against Ren's wishes to befriend Scissors. This results in Sudo tricking Shinji into giving his name, Knight's human identity and Yui's address as he attempts to kill the Riders while kidnapping Yui to have leverage over her brother. By then, both Ren and Reiko realized the truth behind Kaga's death as Sudo decides to kill everyone to cover his tracks. In the course of his battle with Knight, Scissor's Rider deck, contract card included, cracked as a result of the two using their Final Vents on each other, after Knight hits his deck first. This resulted with Volcancer devouring its master in an ironic death by betrayal.[1][2][3][4] In the 13 Riders special, Sudo is among the Kamen Riders that attack Shinji by pretending to be an ally. He is slain by Takeshi due to his issue with police officers.

While Sudo's death is later averted once the Rider War comes to an end, he is succeeded as Scissors by Ishibashi in Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story.

Masashi Sudo is portrayed by Takeshi Kimura (木村 剛, Kimura Takeshi).

Miyuki Tezuka (手塚 海之, Tezuka Miyuki) is a 24-year-old mysterious and enigmatic fortune-teller who believes in predestination, another Kamen Rider that Kanzaki did not personally pick to have a Rider deck. The real chosen one was his friend Yuichi Saito (斉藤 雄一, Saitō Yūichi), an excellent pianist who lost ability to play when a mugger (later revealed to be Takeshi Asakura) broke his hands. After his friend was devoured by a Guldthunder after refusing Kanzaki's offer to fight in the Rider War, Miyuki takes the Rider deck on his behalf and becomes Kamen Rider Raia (仮面ライダーライア, Kamen Raidā Raia) to avenge his friend by ending it. While trying to convince Ren that he has no chance of winning due to his self-doubt, Miyuki meets Shinji and becomes their ally. Shiro would later attempt to escalate the battle by giving Miyuki one of two Survive cards, but he passes it to Ren instead. Miyuki would later avenge Yuichi by destroying Guldthunder before being killed by Ouja later on after taking a fatal hit meant for Ryuki in an act of defying fate.[1][2][3][4] In the 13 Riders special, Tezuka is slain by Itsuro.

Miyuki Tezuka is portrayed by Hassei Takano (高野 八誠, Takano Hassei).

Jun Shibaura (芝浦 淳, Shibaura Jun) is a 21-year-old 2nd year college student at Meirin University, extremely well-versed in computers and programming to be in the Matrix gaming club. Being the son of a company president, Jun is arrogant in personality and toys with other people's lives for nothing more than a good laugh. He joined the Rider War simply to be the winner as it was all a game to him, transforming into Kamen Rider Gai (仮面ライダーガイ, Kamen Raidā Gai).

Manipulating his fellow members into killing each other in a game, Jun meets Shinji and later steals his contract card from him to use both it and the virus he uploaded to the ORE Journal mainframe to become the head of their company. But Shimada's own hacking skills and Miyuki foiled Jun's plans as he is arrested soon after. However, his father was able to bail him out with Shuichi's aid. After learning the other Riders' identities, Jun kidnaps Yui to start a "Rider party" between him, Knight, Raia, and Ryuki. However, in the middle of the fight, their battle gets intertwined with the one between Zolda and Ouja, who used Gai as a shield to take the brunt of Zolda's Final Vent before killing him with his own hands.[1][2][3][4] In the 13 Riders special, Shibaura is among the Kamen Riders that attack Shinji. He is later eaten by a Despider.

Jun Shibaura is portrayed by Satoshi Ichijo (一條 俊, Ichijō Satoshi).

Itsuro Takamizawa (高見沢 逸郎, Takamizawa Itsurō) is the main antagonist of Kamen Rider Ryuki Special: 13 Riders, which takes place in one of the alternate continuities in the Ryuki timeline, a 38-year-old rich and charismatic businessman of the Takamizawa Group who is able to transform into the chameleon-themed Kamen Rider Verde (仮面ライダーベルデ, Kamen Raidā Berude) with the aid of his Contract Monster Biogreeza. He joined the Rider War to add to his already massive wealth so he could take control of the world.[3][4][5] He killed Raia and then fatally wounded Ren before being killed by Ren.

In Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story, Takamizawa is absent with Kimura taking his place as Verde.

Itsuro Takamizawa is portrayed by Arthur Kuroda (黒田 アーサー, Kuroda Āsā).

Satoru Tojo (東條 悟, Tōjō Satoru) is a 25-year-old disturbed man with a twisted moral background; a social outcast determined to do whatever it takes to be accepted. However, Tojo also seemed to have a great amount of respect for his teacher, Hideyuki Kagawa, adopting his theories on the concept of heroism, although Tojo develops a hero syndrome due to his bloodthirsty nature. Due to Tojo's history of mental instability, he came to believe that he needed to kill those he loved or cared about to become a hero, as his grief would make him fight harder. Becoming Kamen Rider Tiger (仮面ライダータイガ, Kamen Raidā Taiga), Tojo aided Kagawa on the goal to close the Mirror World. However, killing Kagawa because of his ideologies, Tojo joined the Rider War to prove himself as a true hero and to prove that his twisted version of Kagawa's ideals is correct.

However, these actions result in a downward spiral of contradictions for Tojo as he tries to win by any means, from betraying Sano to an attempt to trap the other Riders in the Mirror World by destroying their only way out. But as he runs off from committing the latter, Tojo saw a father and son, briefly reminding him of Kagawa and his own child. However, a truck was about to crash into the two, and Tojo sacrificed himself to save them at the cost of his own life. Ironically, the following day, a newspaper featured an article on Tojo's good deed and labeled a hero.[1][3] When time is reset, Tojo is restored to life, though he does apologize to Shinji for bumping into him.[4] In the 13 Riders special, Satoru is among the Kamen Riders that attack Shinji.

While Tojo's death is later averted once the Rider War comes to an end, he is succeeded as Tiger by Totsuka in Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story.

Satoru Tojo is portrayed by Jun Takatsuki (高槻 純, Takatsuki Jun).

Mitsuru Sano (佐野 満, Sano Mitsuru) is the 21-year-old son of a wealthy businessman who worked in a parking garage, occasionally cleaning rich people's cars, although he came from an affluent family. His father sent him out into the world so that he could learn the hardships of life and not be spoiled by a rich upbringing. Because of his poor lifestyle, he believed friendship, respect, and love could be bought, and thus accepted Shiro Kanzaki's proposal to become Kamen Rider Imperer (仮面ライダーインペラー, Kamen Raidā Inperā) in order to become rich and lead a happy life. He became a mercenary of sorts, attempting to sell his strength as a Kamen Rider to the various factions within the remaining Riders.

After seeing he cannot worm out of being a Kamen Rider after finally inheriting his father's business and having no longer any need to fight, Sano decides to buy the services of the other Riders to fight his battles for him. However, the attempts ended in failure before he decides to team up with Tojo and befriended him. However, after being literally back-stabbed by Tojo and left for dead, Sano attempted to get back to the real world when he was ambushed by Ouja, who destroys his Rider deck. Unable to leave the Mirror World, Sano screams for help as he dissolves within minutes.[3][4] In the 13 Riders special, Sano is among the Kamen Riders that attack Shinji.

While Sano's death is later averted once the Rider War comes to an end, he is succeeded as Imperer by Ishida in Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki side story.

Mitsuru Sano is portrayed by Takashi Hyuga (日向 崇, Hyūga Takashi).

Miho Kirishima (霧島 美穂, Kirishima Miho) is a character who only appeared in one of the alternate continuities detailed in Kamen Rider Ryuki: Episode Final, an 18-year-old con artist who seduces wealthy men in order to steal their money and/or valuables. Miho accepted Shiro's proposal to join the Rider war for two reasons: she wanted to resurrect her sister and take revenge on her killer Takeshi Asakura. She fights as Kamen Rider Femme (仮面ライダーファム, Kamen Raidā Famu) to reach this goal, in which she succeeds in defeating Takeshi, but is killed by Mirror Shinji when he exploited her love for Shinji. She is the first official female Kamen Rider.[3][4] In the 13 Riders special, Miho is among the Kamen Riders that attack Shinji.

Miho Kirishima is portrayed by Natsuki Katō (加藤 夏希, Katō Natsuki).

In the alternate continuity of the Ryuki timeline depicted in Kamen Rider Ryuki: Episode Final, Yui Kanzaki had already met and befriended Shinji Kido when they were still both very young. As a result, the young and lonely Yui subconsciously created a duplicate of Shinji in the imaginary Mirror World. The Mirror World version of Shinji Kido, referred as "Mirror Shinji Kido" (鏡像の城戸 真司, Kyōzō no Kido Shinji), could survive indefinitely in his own universe without any extra protection, but could only stay in the real world for a short time before starting to disintegrate, just like how a normal human would in the Mirror World. Several years later, the doppelganger adopts the identity of Kamen Rider Ryuga (仮面ライダーリュウガ, Kamen Raidā Ryūga) and joins the Rider War in order to pursue his goal of becoming a real person in the real world. After killing Miho, the Mirror Shinji attempts to merge with Shinji in order to survive, but the real world Shinji forces him out and fights him, resulting in his death due to a match between their long duel, and a clash of two Final Vents.[3][4]

In Kamen Rider Zi-O and its Rider Time Ryuki side story, a main universe version of Mirror Shinji was created as an embodiment of Shinji's darkest aspects when he constantly blamed readers of the ORE Journal for their part in his workplace's disbandment. While briefly employed by the Time Jackers until Shinji accept him, Mirror Shinji becomes his universe's version of Kamen Rider Ryuga and attempts to absorb Shinji and before Ren and Shinji forced him out of the latter's body with Ryuki defeating him.

Takamasa Suga portrays Mirror Shinji Kido as well as Shinji Kido in a dual role.

Yui Kanzaki (神崎 優衣, Kanzaki Yui) is a 19-year-old woman who had been aiding Ren prior to the series. Yui's purpose for joining Ren is to find clues about her long-lost brother Shiro Kanzaki. But unbeknownst to her, she has a mysterious connection with Mirror World and its monsters.[1]

Yui Kanzaki is portrayed by Ayano Sugiyama (杉山 彩乃, Sugiyama Ayano).

Sanako Kanzaki (神崎 沙奈子, Kanzaki Sanako) is Shiro's and Yui's 45-year-old aunt who is the owner of coffee shop Atori (花鶏). She took an immediate dislike for the hard as nails Ren, but welcomed the clumsy Shinji with open arms. Sanako considers herself to be a wise woman and says that her intuition is never wrong.

Sanako Kanzaki is portrayed by Kazue Tsunogae (角替 和枝, Tsunogae Kazue).

Shiro Kanzaki (神崎 士郎, Kanzaki Shirō) is the 25-year-old mysterious man and scientific genius who created the Kamen Riders for the purpose of creating the Rider War, with Kamen Rider Odin as his right-hand man. He is Yui's older brother, who was taken to live with his relatives in America thirteen years prior to the start of the series. While researching the Mirror World, Kanzaki was claimed to be killed, but in reality, he merged with his Mirror World double to survive in the Mirror World, then he created the Kamen Riders and developed the ability to reverse the flow of time. Though cruel, Kanzaki's intent for the Rider War was to prevent Yui from dying on her twentieth birthday. At the end of the series, Kanzaki honors his sister's wishes and uses his chrono kinesis to change history so that Yui remains dead, thus negating the Mirror World and Rider War and all the deaths that occurred because of them.[1][2][3][4]

Shiro Kanzaki is portrayed by Kenzaburo Kikuchi (菊地 謙三郎, Kikuchi Kenzaburō).

Daisuke Okubo (大久保 大介, Ōkubo Daisuke) is the 36-year-old editor and Shinji's senior. He can be a bit silly at times.

Daisuke Okubo is portrayed by Kanji Tsuda (津田 寛治, Tsuda Kanji).

Reiko Momoi (桃井 令子, Momoi Reiko) is a 24-year-old no-nonsense journalist whose goal is to uncover the truth behind the disappearances that are inextricably linked to the Rider War. She also became Shuichi's target for unwanted affections.

Reiko Momoi is portrayed by Sayaka Kuon (久遠 さやか, Kuon Sayaka).

Nanako Shimada (島田 奈々子, Shimada Nanako) is a 25-year-old systems operator who works for the ORE Journal.

Nanako Shimada is portrayed by Hitomi Kurihara (栗原 瞳, Kurihara Hitomi).

Megumi Asano (浅野 めぐみ, Asano Megumi) is a 25-year-old woman who used to be Shuichi's secretary. She returned into his life claiming that the two of them were to be married. Megumi is a strong individual and quite capable in a fight, which is why Shuichi hired her as his bodyguard. However, she is quite clumsy, which was why Shuichi had fired her. She would later be hired by Okubo as a journalist for ORE.

Megumi Asano is portrayed by Chisato Morishita (森下 千里, Morishita Chisato).

Hajime Nakamura (仲村 創, Nakamura Hajime) is a 27-year-old graduate student at Seimeiin University. He was originally one of the staff under Professor Ejima at Lab 401, but he was sick the day Kanzaki and Ejima began their experiments. Upon learning what occurred, Nakamura never forgave Kanzaki and his sister, for the events that occurred. Nakamura studiously avoided any questions about the lab, Kanzaki and what happened there, when encountered by Yui when she came to Seimeiin University to learn more about her brother's actions and later Reiko and Shinji (though Kagawa had given him some superficial explanation). Nakamura eventually joined Professor Kagawa to stop the Rider War as Alternative (オルタナティブ, Orutanatibu). However, Nakamura's reasons were for vengeance and thus was killed by Tojo because of those reasons.[1][3][4]

Hajime Nakamura is portrayed by Junichi Mizuno (水野 純一, Mizuno Jun'ichi).

Hideyuki Kagawa (香川 英行, Kagawa Hideyuki) is a 37-year-old professor at Seimeiin University who has his wife Noriko (典子) and son Yuta (裕太, Yūta). Prior to Kanzaki's experiment, Kagawa wandered into Lab 401 one day and happened to see Shiro Kanzaki's notebook lying on the floor. He scooped it up, opened it and gave every intriguing page a once-over glance before Kanzaki snatched it from him. However, Kagawa had photographic memory and remembered what he had read. After learning the severe nature of Kanzaki's experiments, yet by his own admittance does not fully understand what is happening, Kagawa began to duplicate Kanzaki's work in order to close the Mirror World. To that end, he formed a relationship with Satoru Tojo and Nakamura. Kagawa eventually created the Alternative Decks, eventually using one himself to become Alternative Zero (オルタナティブ・ゼロ, Orutanatibu Zero).[1][3][4]

Hideyuki Kagawa is portrayed by Satoshi Jinbo (神保 悟志, Jinbo Satoshi).

The contract monsters (契約モンスター, Keiyaku Monsutā) used by the Kamen Riders are also Mirror World monsters, serving as their respective rider's power source in return for absorbing the energy of a defeated Mirror World monster. But if the energy is not absorbed, it reforms into a new Mirror World monster. Despite some contract monsters willing to attack their Kamen Riders if not properly fed or the contract become null and void, some display a sense of loyalty in avenging their master by going after their killer.

Dragreder (ドラグレッダー, Doragureddā)

A red mechanical Japanese dragon contract monster under Ryuki, later gained enough power to evolve into Dragranzer (ドラグランザー, Doraguranzā).

Dragblacker (ドラグブラッカー, Doraguburakkā)

A black mechanical Japanese dragon contract monster under Ryuga and it is a dark version of Dragreder.

Darkwing (ダークウイング, Dākuuingu)

A giant mechanical vampire bat-like contract monster under Knight, later gained enough power to evolve into Darkraider (ダークレイダー, Dākureidā).

Volcancer (ボルキャンサー, Borukyansā)

A mechanical humanoid crab-like contract monster under Scissors, using its large claws to fight. Voiced by Yoshimasa Chida (千田 義正, Chida Yoshimasa).

Magnugiga (マグナギガ, Magunagiga)

A giant Minotaur-like robot that is Zolda's contract monster. Likely due to the size of the costume, it never fights on its own and is only summoned for Zolda's Final Vent.

Evildiver (エビルダイバー, Ebirudaibā)

A flying mechanical stingray monster that was originally Raia's contract monster, serving as a glider Raia rides on for ramming attacks, later becoming Ouja's contract monster.

Metalgelas (メタルゲラス, Metarugerasu)

An armored humanoid rhinoceros monster that was originally Gai's contract monster before Ouja acquired it.

Venosnaker (ベノスネーカー, Benosunēkā)

The largest of the Mirror World monsters, it is giant mechanical cobra monster with acidic spit that is Ouja's contract monster.

Genocider (ジェノサイダー, Jenosaidā)

After Ouja acquired Evildiver and Metalgelas, he uses the Unite Vent card to merge them with Venosnaker to form the Chimera-like Genocider where it has the head and tail of Venosnaker, the horns and body of Metalgelas, and Evildiver on its back where its wings have opened up in different directions. Its breastplate can produce a black hole when the Final Vent associated with it is activated.

Destwilder (デストワイルダー, Desutowairudā)

An armored humanoid white tiger monster that is Tiger's contract monster.

Gigazelle (ギガゼール, Gigazēru)

Humanoid gazelle monsters that are Imperer's contract monsters, often accompanied by Megazelle (メガゼール, Megazēru), Negazelle (ネガゼール, Negazēru), Omegazelle (オメガゼール, Omegazēru), and Magazelle (マガゼール, Magazēru). Prior to Imperer's appearance, the gazelle monsters were wild Mirror World monsters and still have traces in occasionally attacking Imperer while summoned to support him.

Goldphoenix (ゴルトフェニックス, Gorutofenikkusu)

A mechanical phoenix monster that is Odin's contract monster.

Biogreeza (バイオグリーザ, Baiogurīza)

A humanoid chameleon monster that is Verde's contract monster.

Blancwing (ブランウイング, Buran'uingu)

A mechanical swan monster that is Femme's contract monster.

Psycorogue (サイコローグ, Saikorōgu)

A robotic humanoid cricket monster that is Alternative Zero's contract monster and can transform into a motorcycle called the Psycoroader (サイコローダー, Saikorōdā). Survived its master upon being controlled by Yui, it was weakened by Ryuki to be destroyed by Knight.

The following monsters might appear to be their own monster classes, being the only ones of their kind to appear with no variations:

• Deadlemur (デッドリマー, Deddorimā, 13 & 14): A three-eyed lemur/tarsier sniper-type monster that roamed around the elevators of Le Crock, starting an urban legend. Destroyed by Knight's Final Vent and absorbed by Dragreder. Voiced by Katsumi Shiono (塩野 勝美, Shiono Katsumi).
• Gelnewt (ゲルニュート, Gerunyūto, 17 & 18): A humanoid newt monster that wielded a shuriken as its weapon. Destroyed by Ryuki's Final Vent. Voiced by Katsumi Shiono.
• Sonorabuma (ソノラブーマ, Sonorabūma, 29, 38): A cicada monster that targeted Shimada when Reiko and Shimada were abducted. It was kicked by Ryuki into the mirror and destroyed by one of Zolda's Shoot Vents and Knight's Final Vent. A second Sonorabuma appeared in episode 38, only to be destroyed by Knight's Final Vent. Voiced by Katsumi Shiono.
• Brobajell (ブロバジェル, Burobajeru, 33, 43 & 44): A jellyfish monster that used the electrodes on its forearms to kill its prey. Destroyed by Ryuki's Final Vent. From the end of episode 43 to the beginning of episode 44, a Brobajell was among the Mirror World monsters that helped to protect Yui. Voiced by Katsumi Shiono.
• Fake Kamen Rider Agito (偽仮面ライダーアギト, Nise Kamen Raidā Agito, Hyper Video): Labeled as the ruler of Mirror World, he is the mirror version of Kamen Rider Agito's Burning Form. He gathered the Mirror World monsters in a plan to destroy the Kamen Riders, which confused Ryuki to see the monsters actually use teamwork. But once Agito arrived, Ryuki found out his Final Vent had no effect on the Fake Agito. Though it took Ryuki and Agito's Double Rider Kick to destroy him, Fake Agito was actually a dream and nothing more.

Though one type of Spider monster appeared in the show, three human-like types appeared in the 13 Riders special (though they made cameos in the show).

• Dispider (ディスパイダー, Disupaidā, 1 & 2): The first of the Mirror World monsters Shinji encountered, a giant gold and white Spider-like monster that targeted women like Megumi Ida. Though destroyed by Knight's Final Vent, Dispider was not absorbed by Darkwing and was reformed into a drider version of itself named "Dispider Reborn" (ディスパイダー・リ・ボーン, Disupaidā Ri Bōn), now attacking men as well. It was finally destroyed by Ryuki's Dragon Rider Kick and absorbed by Dragreder. In the 13 Riders special, a purple and brown-colored Dispider was the Mirror Man's final defense, devouring Gai before being destroyed by Knight Survive's Final Vent. Voiced by Jin Yamanoi (山野井 仁, Yamanoi Jin).
• Mispider (ミスパイダー, Misupaidā, 43, 44 & 13 Riders): A Purseweb spider monster. It appeared among the Mirror World monsters that helped to protect Yui. Another appeared, attempting to eat a young girl, but it was killed by the Riders during the fight. Voiced by Mie Odagi (小田木 美恵, Odagi Mie).
• Respider (レスパイダー, Resupaidā, 43, 44 & 13 Riders): It is a Jorō spider monster. It appeared among the Mirror World monsters that helped to protect Yui. Another appeared to aid another Mispider and a third Solospider, but both were killed by the Riders during each fight. Voiced by Mako Hyōdō (兵藤 まこ, Hyōdō Mako).
• Solospider (ソロスパイダー, Sorosupaidā, 43, 44 & 13 Riders): A green armored Tetragnatha praedonia monster. A second appeared to fight the Riders when they got near to the Mirror Man. Voiced by Katsumi Shiono.

Zelles are humanoid gazelle monsters that usually attack in groups, sneaky and blindingly fast with the ability to jump distances. Despite being rogue Mirror World monsters, they usually travel with Kamen Rider Imperer because of his contract to Gigazelle even appearing when he uses his Final Vent.

• Gigazelle: The soldier Zelles. A gold Gigazelle appeared in episode 3 to attack a girl and was destroyed by Ryuki's Strike Vent. A green-and-yellow Gigazelle appeared and was destroyed by Ryuki's Final Vent in the next episode. A third quickly appeared and was destroyed by Zolda's Shoot Vent without trouble. By episode 39, as a prelude to Impaler's arrival, a dozen Gigazelles were on the attack until they were all wiped out by Ryuki Survive's Final Vent. A Gigazelle appeared in Shinji's dream during the Hyper Video special. It was destroyed by Ouja's Final Vent.
• Megazelle (メガゼール, Megazeēru, 3 & 4): A blue-and-yellow Zelle that devoured a school teacher before Ren could stop it, making it personal. Knight destroys the monster with his Final Vent, and it is absorbed by Darkwing. Voiced by Izumi Kikuchi (菊池いづみ, Kikuchi Izumi).
• Negazelle (ネガゼール, Negazēru, 24): A gazelle/cape buffalo-type Zelle that interfered in the fight between Ouja and Knight Survive. This monster was killed by Knight Survive's Final Vent. Voiced by Yoshimasa Chida.
• Omegazelle (オメガゼール, Omegazēru, 24, 25 & 39): A gazelle/water buffalo-type Zelle. It used a staff in battle. Targeted Shinji and Ren while Shiro Kanzaki calls off the Riders' battle, before being destroyed by Ryuki's Final Vent. Another appeared in episode 39 leading a pack of Gigazelles until it was destroyed by Ryuki Survive's Final Vent. Voiced by Yoshimasa Chida.
• Magazelle (マガゼール, Magazēru, 39, 44): A bighorn sheep/gazelle-type Zelle. The first one was encountered in episode 39 and destroyed by Tiger's Final Vent. Another appeared in 44 was destroyed by Ryuki's Dragon Rider Kick. Voiced by Katsumi Shiono.

Zebraskulls are zebra monsters able to stretch their bodies, using the blades on their forearms to slice and dice prey. Voiced by Yoshimasa Chida.

• Zebraskull Iron (ゼブラスカル・アイアン, Zeburasukaru Aian, 6-8): A white-headed Zebra monster that Zolda battled before it escape him. This monster ran loose until it fought Ryuki and was killed by his Final Vent.
• Zebraskull Bronze (ゼブラスカル・ブロンズ, Zeburasukaru Buronzu, 7): A black-headed Zebra monster that is a servant to Zebraskull Iron. This monster supported Iron until it was destroyed by one of Zolda's Shoot Vents.

Boarders are wild boar-like Mirror World monsters that use their bodies as weapons in charge attacks. Voiced by Yoshimasa Chida.

• Wildboarder (ワイルドボーダー, Wairudobōdā, 9 & 10): A red wild boar monster that first appearing when Shimada was kidnapped by a man with a grudge against ORE Journal who just wanted to pay for his wife's surgery. Moving with incredible speed, Wildboarder grabbed the kidnapper and dragged him into the Mirror World, unwittingly setting Shinji up as the crook with Knight attempting to kill the monster when Zolda interfered. When the monster later tries to eat the kidnapper's daughter Yukari, Ryuki and Knight fight it until Zolda takes advantage to destroy them all, with Wildboarder destroyed during the onslaught of Zolda's Final Vent.
• Shieldboarder (シールドボーダー, Shīrudobōdā, 29, 30, 43, & 44): A blue wild boar monster. This monster is able to use its chest armor as a shield. This monster was destroyed by Ryuki's Final Vent.

Biters are longhorn beetle-like monsters armed with boomerang sabers.

• Zenobiter (ゼノバイター, Zenobaitā, 11, 38, 43 & 44): A blue-colored male longhorn beetle monster. He feasted on people in a train car on the Fukutoshin Line. Though he keeps Ryuki from getting to his weapons, the monster is tricked as he is then destroyed by Ryuki's Final Vent. A second Zenobiter appeared in episode 38, only to be destroyed by Knight's Final Vent. From the end of episode 43 to the beginning of episode 44, a Zenobiter was among the Mirror World monsters that helped protect Yui. Voiced by Katsumi Shiono.
• Terabiter (テラバイター, Terabaitā, 11 & 12): A red-colored female longhorn beetle monster. She pursued Professor Hitoshi Ejima though held at bay by the Seal card he had on his person. But once he loses the card, Terabiter almost devoured him when Shinji and Ren come to his aid in time. Destroyed by Ryuki's Knight's Final Vents, and absorbed by Darkwing after Knight keeps Dragreder from doing the same instead. Voiced by Yumi Takada (高田 由美, Takada Yumi).

Krakens are squid-like monsters that have different weapons and the tops of their heads are octopus-shaped. Voiced by Yoshimasa Chida.

• Bakraken (バクラーケン, Bakurāken, 15): A blue squid monster with a light blue chest. It wields a tentacle-like whip in battle. It attacked the surviving member of the computer club. This monster was destroyed by Gai's Final Vent.
• Wiskraken (ウィスクラーケン, Wisukurāken, 15, 16, 38, 43 & 44): A blue squid monster with a red chest. It wields a staff in battle. Wiskraken witnessed the death of Bakraken and later fought Kamen Rider Ryuki. It was destroyed by Ryuki's Final Vent. A second Wiskraken appeared in episode 38, only to be destroyed by Knight's Final Vent.

Gulds are Kanzaki's bird-like Mirror World monsters, serving him in maintaining the Rider War by eliminating those who refuse to fight and those who get too noisy in his affairs. Guld means "Gold" in Danish. Voiced by Katsumi Shiono.

• Guldthunder (ガルドサンダー, Garudosandā, 22, 42): A red Fenghuang monster in a Phoenix-shaped helmet. It can attack with its retractable tail and use fire attacks. It devoured Yuichi under Kanzaki's orders when Yuichi turned down Kanzaki's offer. It was later used by Kanzaki to attack Kamen Rider Raia. Destroyed by Raia's Final Vent. Originally designated to be the Contract Monster of Yuichi in concept arts in the event that Yuichi accepted Kanzaki's offer. s
• Guldstorm (ガルドストーム, Garudosutōmu, 35, 39, 40, 43, 44 & 48): A red-and-black Fenghuang monster with a tribal personality that wields a tomahawk weapon and wears a turkey-feathered headdress. Destroyed by Tiger's Final Vent. Another one appeared in episode 39, where it was used by Kanzaki to save Yui from Psycorogue, before used to target Kagawa's family to blackmail him into giving up the Alternate Vent. But the monster was quickly driven away by Dragreder. From the end of episode 43 to the beginning of episode 44, a Guldstorm was among the monsters that helped protect Yui. In episode 48, Kanzaki had it prevent Yui's suicide and take her where she would not try it again.
• Guldmirage (ガルドミラージュ, Garudomirāju, 35, 43 & 44): A green armored Fenghuang monster with Peacock feathers designed on its armor. It wields a ring-shaped weapon. This monster was destroyed by Ryuki Survive's Shoot Vent.

Abysses are shark-like Mirror World monsters that, in Kamen Rider Decade, are contracted to Kamen Rider Abyss. They are capable of shooting water at enemies. Voiced by Katsumi Shiono.

• Abysshammer (アビスハンマー, Abisuhanmā, 26, 43, & 44): A Hammerhead shark monster with machine guns and missile launchers. It targeted a client of Kitaoka. Destroyed by Ryuki's Strike Vent and one of Zolda's Shoot Vents.
• Abysslasher (アビスラッシャー, Abisurasshā, 27, 43 & 44): A Shark monster with two saw-like swords and water-spewing abilities. It targeted a child named Takuya. Destroyed by Knight Survive's Final Vent.

Buzzstingers are humanoid bee monsters that usually attack in groups. A trio of Buzzstingers first appear to target Mika, the only survivor of their attack on an ocean liner after being saved by Asakura to be used by him in order to feed his monsters. The trio used the "Trinity" attack to counter any Final Vent attack until they were all destroyed by Ouja's and Knight's Final Vents with one of Zolda's Shoot Vents from all three directions at once. Their essence was soon devoured by Venosnaker, Metalgelas, and Evildiver despite the prevention attempts from Darkwing and Dragreder. A pair of Buzzstingers appeared in episode 37 to target Eri after she came out of her coma. Voiced by Katsumi Shiono.

• Buzzstinger Hornet (バズスティンガー・ホーネット, Bazusutingā Hōnetto, 31 & 32): A red-armored hornet monster attempted to target Mika. This monster wields needle-blade daggers as weapons.
• Buzzstinger Wasp (バズスティンガー・ワスプ, Bazusutingā Wasupu, 31 & 32): A blue-armored digger wasp monster that attempted to target Mika. This monster wields a sword as his weapon.
• Buzzstinger Bee (バズスティンガー・ビー, Bazusutingā Bī, 31 & 32): A yellow-armored honey bee monster that attempted to target Mika. This monster wields a bow and arrow.
• Buzzstinger Broom (バズスティンガー・ブルーム, Bazusutingā Burūmu, 37, 43 & 44): A gold-armored carpenter bee monster. It wields a bow and arrow in battle. This monster was destroyed by Knight Survive's Final Vent.
• Buzzstinger Frost (バズスティンガー・フロスト, Bazusutingā Furosuto, 37, 43 & 44): A silver-armored Scoliidae monster. It wields needle-blade daggers in battle. This monster was destroyed by Ryuki Survive's Final Vent.

Sheerghosts (シアゴースト, Shiagōsuto, 41 & 43-47) are Dragonfly Mirror World monsters that make their presence known in the Rider War end-game in the TV series (41 and after) and Episode Final, where Yui's new life is almost used up. They are actually larval Mirror World monsters, able to shoot silk from their mouths to escape or capture prey. The first two were encountered in episode 41, where one was destroyed by Kamen Rider Ryuki Survive's Shoot Vent, while the second one was destroyed by Impaler's Final Vent. From the end of episode 43 to the beginning of episode 44, some Sheerghosts were among the Mirror World monsters that converged on Yui only to be repelled by the Mirror World monsters on Kanzaki's side while one helped to protect Yui. In episode 45, three Sheerghosts tried to attack Yui only to be destroyed by Knight's Final Vent and Ryuki Survive's Shoot Vent. At the same time, a bunch of them were destroyed by Zolda's Final Vent. In episode 46, a bunch of them crashed the fight between Kamen Rider Knight, Kamen Rider Zolda, and Kamen Rider Ouja. The ones that engaged Kamen Riders Ouja and Zolda were destroyed by a Final Vent/Shoot Vent combo. The ones that fought Kamen Rider Knight were destroyed by his Final Vent, while the others were destroyed by Ryuki's Strike Vent. In episode 47, a bunch of them attacked Ryuki Survive and Knight Survive, but they managed to give the Sheerghosts the slip. Those Sheerghosts then crouched down on the ground and evolved into Raydragoons. Voiced by Hiroyuki Shibamoto. Shigenori Sōya (宗矢 樹頼, Sōya Shigenori). Yoshimasa Chida. Katsumi Shiono.

• Raydragoons (レイドラグーン, Reidoragūn, 47-49): Blue dragonfly monsters with dragonfly tails on the back of their heads that are the evolved forms of the Sheerghosts. They have blade-like structures on their forearms and are capable of flight. They first appeared in episode 47, where they evolved from the Sheerghosts that pursued Ryuki and Knight. In episode 48, a bunch of them fought Kamen Rider Ouja and were defeated. In episode 49, the Raydragoons attacked the city on the final day of the Rider War. One stabbed Shinji in the back when he saved a young girl. They were destroyed by Ryuki Survive and Knight Survive's Final Vents. Voiced by Hiroyuki Shibamoto. Shigenori Sōya. Yoshimasa Chida. Katsumi Shiono.
• Hydragoon (ハイドラグーン, Haidoragūn, 42, Episode Final): Blue dragonfly monsters that are the alternate evolved forms of the Sheerghosts. The Hydragoons are more dragonfly-like than the other forms and are much larger. They are shown at the end being overpowered by Dragranzer and Darkraider.

Eri Ogawa (小川 恵里, Ogawa Eri) is the 24-year-old fiancé of Ren Akiyama who ended up in a coma when attacked by Darkwing the moment Kanzaki opened a link to the Mirror World, with Ren participating in the Rider War so he can reawaken her while making regular visits to her hospital room. Ren succeeds in reviving Eri once named the winner of the Rider War by default, though he died from his injuries soon after with the Rider War's events are averted soon after.

By the events of Kamen Rider Zi-O's Rider Time: Kamen Rider Ryuki storyline, Eri works as a nurse in the hospital she was placed at during her coma.

Eri Ogawa is portrayed by Mahiru Tsubura (つぶら まひる, Tsubura Mahiru).

Hitoshi Ejima (江島 均, Ejima Hitoshi) is a former professor at Seimeiin University, he was the one who help Kanzaki perform the experiment that resulted with Eri's coma. Since then, Ejima left the university and wandered the city with a Seal card in hand to protect himself from the Mirror World monsters. But once he loses the card, Ejima ran back to his lab to plea Kanzaki to help him as he's attacked by a Terabiter. Though saved from the monster, Ejima dies of a heart attack as he sees Yui and laments that she should have never been born.

Hitoshi Ejima is portrayed by Senzaburo Makimura (牧村 泉三郎, Makimura Senzaburō).

Koichi Sakakibara (榊原 耕一, Sakakibara Kōichi) is a 28-year-old man who lives in an apartment where Shinji found a Rider deck that leads him to become Kamen Rider Ryuki. He disappeared prior to the start of the series, eaten by Dragreder. In Kamen Rider Ryuki Special: 13 Riders, Sakakibara is the original Ryuki before the latter passes his deck to Shinji as he dissolves inside the Mirror World.

Koichi Sakakibara is portrayed by Keiichi Wada (和田 圭市, Wada Keiichi).