Shinji Kido is a kind-hearted, friendly, simple, and naïve idealist who works at the ORE Journal as a
journalist trainee until he finds one of Shiro Kanzaki's Card Decks, encounters the
Chinese dragon-themed Mirror Monster , and stumbles into the Mirror World while investigating Koichi Sakakibara's disappearance. Despite being told to stay out of the Rider War by Ren Akiyama, Shinji chooses to join anyway to stop the other Mirror Monsters from devouring people and stop the Rider War, forming a contract with Dragreder and becoming Kamen Rider Ryuki in the process. By the series finale, he dies protecting civilians from a pack of Mirror Monsters, but Shiro reverses the Rider War's events, resurrecting its participants and allowing them to resume their normal lives. As Kamen Rider Ryuki, Shinji is equipped with the gauntlet, which allows him to summon Dragreder, the , the gauntlet, and the twin as well as perform the finisher alongside Dragreder with the appropriate Advent Cards. With the card, Shinji can transform into his final form, , and evolve Dragreder into , granting it the ability to assume an alternate motorcycle-like . While transformed, he wields the firearm, which can be reconfigured into the sword. He can also perform the finisher alongside Dragranzer in Bike Mode. Shinji Kido is portrayed by .
Ren Akiyama is a cold loner who fights constantly and is frequently unemployed. Sometime prior to the series, he joined Shiro Kanzaki's Rider War to revive his fiancé, Eri Ogawa, who fell into a coma following an encounter with the
bat-themed Mirror Monster , who he formed a contract with to become . Despite initial reluctance, he befriends Shinji Kido and fights alongside him to stop Mirror Monsters and malicious Rider War competitors until Shinji gives his life saving civilians. Ultimately, Ren faces the last participant, Kamen Rider Odin, in combat until Shiro's sister Yui dies, causing Odin to fade away. Despite becoming the winner by default, Shiro reverses the Rider War, leading to Ren becoming a full-time employee at the Atori coffee shop while Eri is revived in the new timeline. As Kamen Rider Knight, Ren wields the rapier, which allows him to summon Darkwing, the , and copies of himself as well as perform the finisher alongside Darkwing with the appropriate Advent Cards. On its own, Darkwing can mount itself on Ren's back to form the cape-like shield and perform the attack. With the card, Ren can transform into his final form, , and evolve Darkwing into , granting it the ability to assume an alternate Bike Mode. While transformed, he is equipped with the left forearm-mounted
scabbard, which can either separate into the sword and the or be reconfigured into the crossbow. He can also perform the finisher alongside Darkraider in Bike Mode. On its own, Darkraider can perform the attack. Ren Akiyama is portrayed by .
Yui Kanzaki is a young caring woman who had been aiding Ren prior to the series to locate her long-lost brother Shiro Kanzaki. While investigating Shiro's disappearance over the course of the series, she discovers the drawings they made as children served as the basis for the Mirror World's monsters and that, due to their neglectful parents, the real Yui died and allowed her Mirror World counterpart to inhabit her body. Due to being unable to survive outside of the Mirror World, the doppelganger will die on Yui's twentieth birthday, which led to Shiro developing the Rider War in the hopes of saving her. Having repressed these memories, Yui remains unaware of them until the present. Despite Shiro, Ren, and Shinji Kido's best efforts, the Mirror World Yui fades from existence short of the deadline, though her spirit appears before Shiro to tell him she did not want him to save her in the manner he wanted, inspiring him to reverse the Rider War's events. In an alternate ending depicted in the film
Kamen Rider Ryuki: Episode Final, the lonely Yui had met and befriended Shinji as children, but he seemingly abandoned her despite promising not to. Yui was invited by her Mirror World counterpart to play with her, only to learn she will immediately die if she returns to the real world. Yui's doppelganger loaned the original her lifespan, which will last until her twentieth birthday, in exchange for Yui and Shiro's drawings. After joining Ren and Shinji in their fight against the Mirror Monsters in the present, Yui eventually dies, though an angered Shiro does not end the Rider War. Yui Kanzaki is portrayed by .
Shiro Kanzaki is a mysterious scientific genius and Yui's older brother who was taken to live with relatives in America thirteen years prior to the series. He conducted research into the , a parallel dimension opposite to the real world, before he disappeared and was presumed dead. In reality, he merged with his Mirror World counterpart to survive in the Mirror World. In the intervening years, he developed chronokinesis and created thirteen , each with their own set of , belts, and card readers to establish the Rider War in the hopes of averting Yui's death, which is said to take place on her twentieth birthday, by promising to grant the winner one wish in exchange for killing their fellow competitors. By the series finale, Shiro allows Yui to die and honors her dying wish of reversing time to avert the Rider War. Shiro developed the Card Decks and Advent Cards to allow the to survive in the Mirror World by forming contracts with and draw energy from their in return for feeding them the life forces of the Mirror Monsters they destroy. Shiro Kanzaki is portrayed by .
Kamen Rider Zolda is a moniker utilized by its original user and his successor who is aided by their robotic
Minotaur-themed Contract Monster . As Kamen Rider Zolda, the user wields the submachine gun, which allows them to summon Magnugiga, the twin back-mounted , the missile launcher, and the shield as well as perform the finisher alongside Magnugiga with the appropriate Advent Cards.
Shuichi Kitaoka is a self-proclaimed "super-
lawyer" who tends to only help someone if he has something to gain from them and was diagnosed with terminal cancer. With months left to live, he joins Shiro Kanzaki's Rider War as Kamen Rider Zolda with the hopes of achieving immortality and continuing his extravagant lifestyle. However, his condition leaves him vulnerable to fainting spells and dizziness, which eventually forces him to ask his secretary and bodyguard, Goro Yura, to take his place as Zolda during the Rider War's final stages. In an alternate ending depicted in the film
Kamen Rider Ryuki: Episode Final, Kitaoka forfeits the Rider War due to his declining health. During the events of the crossover film
Kamen Rider × Super Sentai: Ultra Super Hero Taisen, the Game World version of Kitaoka transforms into the green-colored , a hybrid of
Midorenger and the
Double Riders. In this form, he commands the
Gokaigers' Gokai Galleon. Shuichi Kitaoka is portrayed by .
Goro Yura is Kitaoka's loyal secretary, bodyguard, and a former client of his who is highly skilled with household work and hand-to-hand combat. Aware of Kitaoka's activities as Kamen Rider Zolda, Goro assists him as much as possible. Due to Kitaoka's cancer, Goro takes over as Zolda to face Takeshi Asakura, dying in the process before Shiro Kanzaki reverses the Rider War's events. Goro Yura is portrayed by .
Takeshi Asakura is a sadistic, cruel, bloodthirsty, arrogant, and bad-tempered criminal with a reputation for loving the act of fighting and killing during his fits of rage after he murdered his entire family as a child. After being represented by Shuichi Kitaoka, who ensured Asakura would remain in prison, the latter joined Shiro Kanzaki's Rider War to satisfy his destructive nature and formed a contract with the giant
cobra-themed Mirror Monster , becoming . With his newfound powers, Asakura breaks out of jail to seek revenge on Kitaoka upon learning of the latter's participation in the Rider War. After receiving Ren Akiyama's help in faking his death to stop the police from interfering with his activities, Asakura kills Kamen Riders Raia and Gai and takes their Contract Monsters as his own. However, the police eventually learn the truth, forcing Asakura to settle his grudge against Kitaoka in a final battle, only to learn his opponent had switched places with Goro Yura, leaving the criminal in disarray over being denied the thing he wanted most before the police kill him. After Shiro reverses the Rider War, revives the participants, and erases their memories of it, Asakura escapes from prison and goes into hiding. Years later, during the events of the web-exclusive series
Kamen Rider Outsiders, Asakura became a hired thug for a corrupt politician before he was betrayed and accepts Kamen Rider Odin's offer to participate in a new Rider Fight to evade arrest, which restores his memories in the process. Asakura subsequently kills his former employer and wins the Rider Fight before learning of Zein from
Kamen Rider Diend and developing an interest in the former. In an alternate ending depicted in the film
Kamen Rider Ryuki: Episode Final, Asakura battles Kamen Rider Femme, who seeks revenge on him for her older sister's murder, before he loses Genocider to Kamen Rider Ryuga and Femme destroys his Card Deck, leaving Asakura to dissolve in the Mirror World. In the web-exclusive special
Kamen Rider Brave: Survive! The Revived Beast Rider Squad,
Foundation X revives this version of Asakura in an artificial body. As Kamen Rider Ouja, Asakura wields the scepter, which allows him to summon Venosnaker and the as well as perform the finisher alongside Venosnaker with the appropriate Advent Cards. After killing Tezuka and Shibaura, Asakura can use their Advent Cards, fuse their respective Contract Monsters Evildiver and Metalgelas with Venosnaker to create the
chimeric , and perform the finisher alongside it. In
Kamen Rider Outsiders, Asakura utilizes Kamen Rider Odin's Survive Mugen card to transform into his final form, , and evolve Venosnaker into a stronger form, granting it the ability to assume an alternate Bike Mode. While transformed, he wields the firearm, which like the Drag Visor Zwei can be reconfigured into a sword. Takeshi Asakura is portrayed by . ==Recurring characters==