Contract Monsters

Once a Mirror Monster is confined, it forms a Contract with the Rider who captured it and becomes labeled a Contract Monster (契約モンスター). However, the Contract Monsters can turn on their human partners and devour them if their Vent Deck is destroyed or should they decide to quit being Riders and thus starve the monster of the energy it would receive from absorbing the energies of other Monsters. Contract Monsters do have a sense of loyalty to their human partners (examples include Darkwing, Blancwing, Destwilder, and Magnugiga). At the same time, some will get angry at their Rider when forced to do something they choose not to do (Dragredder and Gigazelle are prime examples mainly due to the attitudes of their Riders). Then, there are those who completely show utter hatred for their Rider. In Ouja's case, after acquiring Metalgelas and Evildiver; his monsters constantly attack him. However, his unstable mentality and wild personality is more than enough to tame all three of his "pets." Beforehand, Metalgelas and Evildiver loyally served Gai and Raia respectively.


 * Dragreder (ドラグレッダー): A red mechanical Japanese dragon Contract Monster under Kamen Rider Ryuki, later gained enough power to evolve into Dragranzer (ドラグランザー).
 * Darkwing (ダークウイング): A giant mechanical Vampire Bat-like Contract Monster under Kamen Rider Knight, later gained enough power to evolve into Darkraider (ダークレイダー).
 * Volcancer (ボルキャンサー) : A mechanical humanoid Crab-like Contract Monster under Kamen Rider Scissors. It turned on its master and devoured Scissors when his Card Deck was destroyed. This monster was destroyed by Ryuki's Dragon Rider Kick with Darkwing absorbing the monster after Dragreder was told not to.
 * Magnugiga (マグナギガ): A giant Ox-like robot (with a humanoid appearance similar to a minotaur) that is Kamen Rider Zolda's Contract Monster. This monster was destroyed by Ouja's Doomsday in the series.
 * Evildiver (エビルダイバー): A flying mechanical Stingray monster that was originally Kamen Rider Raia's Contract Monster. It becomes a Contract Monster under Ouja when it attempted to avenge its master in vain.
 * Metalgelas (メタルゲラス): An armored humanoid Rhinoceros monster that was originally Kamen Rider Gai's Contract Monster. It becomes a Contract Monster under Ouja when it attempted to avenge its master in vain.
 * Venosnaker (ベノスネーカー): A giant mechanical Cobra monster that is Kamen Rider Ouja's Contract Monster.
 * Genocider (ジェノサイダー): A chimeric Mirror Monster made up of Venosnaker, Metalgelas, and Evildiver. This monster was destroyed in Episode Final by Ryuga's version of the Dragon Rider Kick.
 * Destwilder (デストワイルダー): An armored humanoid White Tiger monster that is Kamen Rider Tiger's Contract Monster. Survived its master and later destroyed by Ryuki Survive's Dragon Firestorm
 * Gigazelle (ギガゼール): A humanoid Gazelle monster. The Gigazelles were originally rogue Mirror Monsters until they became Kamen Rider Imperer's Contracts.
 * Goldphoenix (ゴルドフェニックス): A mechanical Phoenix monster that is Kamen Rider Odin's Contract Monster.
 * Biogreeza (バイオグリーザ): A humanoid Chameleon monster that is Kamen Rider Verde's Contract Monster.
 * Blancwing (ブランウイング): A mechanical Swan monster that is Kamen Rider Femme's Contract Monster.
 * Dragblacker (ドラグブラッカー): A mechanical black Japanese Dragon monster that is Kamen Rider Ryuga's Contract Monster. It is a dark version of Dragredder. It was destroyed alongside its master.
 * Psycorogue (サイコローグ): A robotic humanoid Cricket that is Alternative Zero's Contract Monster. Survived its master upon being controlled by Yui, it was weakened by Ryuki's Drag Claw Fire to be destroyed by Knight's Hishou Zan