The series follows idealist journalist Shinji Kido as he attempts to stop the violent Rider War from claiming more innocent lives than it already has.
Shinji Kido (城戸 真司, Kido Shinji) is a kind-hearted, friendly, simple, and naive 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-like Mirror Monster Dragreder (ドラグレッダー, Doragureddā), and stumbles into the Mirror World while investigating Koichi Sakakibara's disappearance.
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.
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.
On its own, Darkwing can mount itself on Knight's back to form the cape-like Wing Wall (ウイングウォール, Uingu Uōru) shield and perform the Dark Tornado (ダークトーネードー, Dāku Tōnēdō) and Sonic Breaker (ソニックブレイカー, Sonikku Bureikā) attacks.
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.
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.
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.
[1][2][3][4] Shiro developed the Card Decks and Advent Cards to allow the 13 Kamen Riders (13人の仮面ライダー, Jūsan-nin no Kamen Raidā) to survive in the Mirror World by forming contracts with and draw energy from their Contract Monsters (契約モンスター, Keiyaku Monsutā) in return for feeding them the life forces of the Mirror Monsters they destroy.
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.
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.
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-like Mirror Monster Venosnaker (ベノスネーカー, Benosunēkā), becoming Kamen Rider Ouja (仮面ライダー王蛇, Kamen Raidā Ōja).
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.
Forming a contract with the stingray-like Mirror Monster Evildiver (エビルダイバー, Ebirudaibā) and becoming Kamen Rider Raia (仮面ライダーライア, Kamen Raidā Raia), Tezuka seeks to avenge Yuichi by ending the Rider War, joining forces with Ren Akiyama and Shinji Kido in the process.
While transformed, Tezuka is equipped with the left arm-mounted Evil Visor (エビルバイザー, Ebiru Baizā) shield, which allows him to summon Evildiver, the Evil Whip (エビルウィップ, Ebiru Wippu), and copies of other Riders' weapons as well as perform the Hide Venom (ハイドベノン, Haido Benon) finisher alongside Evildiver with the appropriate Advent Cards.
Following a failed attempt at taking over the ORE Journal and serving jail time before his father and Shuichi Kitaoka bail him out, Shibaura learns Kamen Riders Ryuki, Knight, and Raia's identities and invites them to a party in the hopes of killing them.
Kamen Rider Odin (仮面ライダーオーディン, Kamen Raidā Ōdin) is a mysterious golden entity and sentient Card Deck who serves as Shiro Kanzaki's representative in the Rider War and Yui's guardian via host bodies and assistance from the phoenix-like Contract Monster Goldphoenix (ゴルトフェニックス, Gorutofenikkusu).
After joining the Rider War, forming a contract with the anthropomorphic white tiger-like Mirror Monster Destwilder (デストワイルダー, Desutowairudā), and becoming Kamen Rider Tiger (仮面ライダータイガ, Kamen Raidā Taiga), Tojo initially aids his teacher Hideyuki Kagawa in closing the Mirror World before killing him in a twisted attempt at vindicating Kagawa's ideals about heroism.
As a result, Sano became a parking garage worker who cleans cars for other wealthy individuals and developed the belief that friendship, respect, and love could be bought.
[3][4] While transformed, Sano is equipped with the right knee-mounted Gazelle Visor (ガゼルバイザー, Gazeru Baizā), which allows him to summon Gigazelles, among other Zelle-type Mirror Monsters, and the Gazelle Stab (ガゼルスタッブ, Gazeru Sutabbu) double drill gauntlet as well as perform the Drive Divider (ドライブディバイダー, Doraibu Dibaidā) finisher alongside the Zelles with the appropriate Advent Cards.
While transformed, they are equipped with the Slash Visor (スラッシュバイザー, Surasshu Baizā) brace, which allows them to summon Psycorogue and the Slash Dagger (スラッシュダッガー, Surasshu Daggā) sword, transform the former into the Psycoroader (サイコローダー, Saikorōdā) motorcycle, and perform the Dead End (デッドエンド, Deddo Endo) finisher alongside Psycorogue with the appropriate Advent Cards.
She joins the Rider War to resurrect her sister and take revenge on her killer, Takeshi Asakura, forming a contract with the swan-like Mirror Monster Blancwing (ブランウイング, Buran'uingu) to become Kamen Rider Femme (仮面ライダーファム, Kamen Raidā Famu) and falling in love with Shinji Kido in the process.
[3][4] While transformed, Kirishima wields the Blanc Visor (ブランバイザー, Buran Baizā) rapier, which allows her to summon Blancwing, the double-bladed Wing Slasher (ウイングスラッシャー, Wingu Surasshā) staff, the Wing Shield (ウイングシールド, Wingu Shīrudo), which allows her to produce feathery gusts and teleport short distances, and perform the Misty Slash (ミスティースラッシュ, Misutī Surasshu) finisher alongside Blancwing with the appropriate Advent Cards.
As a child, Yui Kanzaki met and befriended Shinji Kido, but was seemingly abandoned by him, which led to her unconsciously creating a Mirror World version of him.
[3][4][5] While transformed, Takamizawa is equipped with the left thigh-mounted Bio Visor (バイオバイザー, Baio Baizā), which allows him to summon Biogreeza, the Bio Winder (バイオワインダー, Baio Waindā) yo-yo, turn invisible, assume other Riders' forms and weapons, and perform the Death Punish (デスパニッシュ, Desu Panisshu) finisher alongside Biogreeza with the appropriate Advent Cards.