Eiji Hino

Kamen Rider Ooz is the main Kamen Rider in Kamen Rider OOO. His title is an approximation of both "Os" and signifies the three medals he uses to transform, as well as meaning "multiple kings" (王ｓ, Ōzu) refering to the title the Greed seek. His debut was a cameo in the film Kamen Rider Double Forever: A to Z/The Gaia Memories of Fate where he fights against the Luna Dopant.

Eiji Hino
Eiji Hino (火野 映司, Hino Eiji, portrayed by Shu Watanabe) (Age: 21) is a young man who has no dreams, no job, and no family. His motto is eating what he can and having at least nothing but the pants on him. He is often scolded by elders for his lifestyle, but liked by others. He is able to live each and every day as one of amazement. Until, a Greed named Ankh gives Eiji the Ooz Driver belt and three medals that can enable him to become the predestined Multi King (複数の王, Fukusū no Ō): Kamen Rider Ooz (仮面ライダーオーズ, Kamen Raidā Ōzu) and to fight the Greed and the Yummies to obtain new medals. During his fight he is approached by the Kogami Foundation and assist him, despite the unclear motives.

Combos
Kamen Rider Ooz can access these forms called "Combos" (コンボ, Konbo) by using three specific O-Medals. There are a total of 36 Combos in total, making him the Kamen Rider with the most forms to date.

Tatoba
Tatoba Combo (タトバコンボ, Tatoba Konbo) is the main default red/yellow/green form accessed by Kamen Rider Ooz. As Tatoba Combo, Ooz wields the Medajalibur sword through the Taka Medal, is armed with the Tora Claw gauntlets, and can execute a Rider Kick called the Tatoba Kick (タトバキック, Tatoba Kikku) through the Batta Medal.

Gatakiriba
GataKiriBa Combo (ガタキリバコンボ, Gatakiriba Konbo) is pure green form when all three Insect medals are used. He has his head having Stag beetle themed powers, his arms Mantis themed powers, and his legs having Grasshopper themed powers.

Litorartar
Litorartar Combo (ライトラーターコンボ, Raitorātā Konbo) is a pure yellow form when all three Field medals are used. He has his head having Lion themed powers, his arms having Tiger themed powers, and his legs having Cheetah themed powers.

Sagorzo
Sagorzo Combo (サゴーゾコンボ, Sagōzo Konbo) is a pure silver form when all three Beast medals are used. He has brute strength due to his head having Rhinoceros themed powers, his arms having Gorilla themed powers, and his legs having Elephant themed powers.

Takakiriba
Takakiriba Combo (タカキリバコンボ, Takakiriba Konbo) is a red/green form with his head having Hawk themed powers, his arms having Mantis themed powers with the Kamakiri Blade gauntlets, and his legs having Grasshopper themed powers. This combo also makes an appearance in Double Forever, to fight the Luna Dopant.

Takatorartah
Takatorartah Combo (タカトラーターコンボ, Takatorātā Konbo) is a red/yellow form with his head having Hawk themed powers, his arms having Tiger themed powers, and his legs having Cheetah themed powers.

Takakireetah
Takakireetah Combo (タカキリーターコンボ, Takakirītā Konbo) is a red/green/yellow form with his head having Hawk themed powers, his arms having Mantis themed powers, and his legs having Cheetah themed powers.

Lakiriba
Lakiriba Combo (ラキリバコンボ, Rakiriba Konbo) is a yellow/green form with his head having Lion themed powers, his arms having Mantis themed power, and his legs having Grasshopper themed powers.

Gatatorartah
Gatatorartah Combo (ガタトラーターコンボ, Gatatorātā Konbo) is a green/Yellow form with his head having Stag beetle themed powers, his arms having Tiger themed powers, and his legs having Cheetah themed powers.

Latoraba
Latoraba Combo (ラトラバコンボ, Ratoraba Konbo) is a yellow/green form with his head having Lion themed powers, his arms having Tiger themed powers, and his legs having Grasshopper themed powers.

Gatatoraba
Gatatoraba Combo (ガタトラバコンボ, Gatatoraba Konbo) is a green/yellow form with his head having Stag beetle themed powers, his arms having Tiger themed powers, and his legs having Grasshopper themed powers.

Lakireetah
Lakireetah Combo (ラキリーターコンボ, Rakirītā Konbo) is a yellow/green/yellow form with his head having Lion themed powers, his arms having Mantis themed power, and his legs having Cheetah themed powers.

Gatakireetah
Gatakireetah Combo (ガタキリーターコンボ, Gatakirītā Konbo): A green/yellow form with his head having Stag beetle themed powers, his arms having Mantis themed powers, and his legs having Cheetah themed powers.

Ooz Driver
The Ooz Driver (オーズドライバー, Ōzu Doraibā) is a belt that gives Eiji the ability to become Kamen Rider Ooz. To transform, Eiji must put three Core Medals in the belt's buckle, angle the buckle, scan the Medals to transfer their energies to the O-Scanner (オースキャナー, Ō Sukyannā), and then hold the O-Scanner up to his chest. By using the O-Scanner on the Medals in the belt, again, which activates a Scanning Charge, Ooz initiates his finishing attack.

O-Medals
The O-Medals (オーメダル, Ō Medaru) are special medals obtained from either a Greed or a Yummy that gives Kamen Rider Ooz different powers based on the animal the Medal represents. Core Medals (コアメダル, Koa Mearu) are colored Medals used to transform into Kamen Rider Ooz or any Combo. Cell Medals (セルメダル, Seru Medaru) are grey Medals and are used in the Medajalibur to activate its powers or in the Ride Vendor to acquire a Candroid. Arms  Legs 
 * Head
 * Taka Medal (タカメダル, Taka Medaru): A Head Core Medal given to Ooz by Ankh. This Medal allows Ooz to see far distances. It also allows Ooz the use of the Medajalibur sword.
 * Kuwagata Medal (クワガタメダル, Kuwagata Medaru): A Head Core Medal which allows Ooz stability.
 * Lion Medal (ライオンメダル, Raion Medaru): A Head Core Medal which allows Ooz to have keen senses.
 * Sai Medal (サイメダル, Sai Medaru): A Head Core Medal which allows Ooz to have a hard and strong head.
 * Kujira Medal (クジラメダル, Kujira Medaru): A Head Core Medal which allows Ooz to see and swim smoothly under water.
 * T-Rex Medal (ティーレックスメダル, Tīrekkusu Medaru):
 * Tora Medal (トラメダル, Tora Medaru): A Arm Core Medal given to Ooz by Ankh. This allows Ooz to use his Tiger Claw (トラクロー, Tora Kurō?) gauntlets as weapons.
 * Kamakiri Medal (カマキリメダル, Kamakiri Medaru): Arm Core Medal obtained from defeating the Mantis Yummy. This allows Ooz to use his bladed gauntlets as weapons.
 * Gorilla Medal (ゴリラメダル, Gorira Medaru): A Arm Core Medal which allows Ooz to fire his large gauntlets at an opponent like missiles.
 * Tako Medal (タコメダル, Tako Medaru): A Arm Core Medal which allows Ooz to use his tentacled gauntlets as weapons.
 * Washi Medal (ワシメダル, Washi Medaru): A Arm Core Medal which allows Ooz the ability of flight.
 * Ptera Medal (プテラメダル, Tera Medaru):
 * Batta Medal (バッタメダル, Batta Medaru): A Leg Core Medal given to Ooz by Ankh. Allows Ooz to execute a Rider Kick and convert the legs into Digitigrade form to jump long distances.
 * Cheetah Medal (チーターメダル, Chītā Medaru): A Leg Core Medal which Allows Ooz to move at blurring speeds.
 * Zo Metal (ゾウメダル, Zō Medaru): A Leg Core Medal which Allows Ooz to cause minor earthquakes with a mere step of his foot.
 * Denki Unagi Medal (電気ウナギメダル, Denki Unagi Medaru): A Leg Core Medal which allows Ooz to generate electricity.
 * Karasu Medal (カラスメダル, Karasu Medaru): A Leg Core Medal which allows Ooz to stand on narrow surfaces.
 * Triceratops Medal (トリケラトップスメダル, Toraiseratoppusu Medaru):

Medajalibur
The Medajalibur (メダジャリバー, Medajaribā) is a sword that serves as Kamen Rider Ooz's main weapon. By inserting three Cell Medals into the Medajalibur and scanning them with the O-Scanner, it can be used to perform a slashing finishing attack called the Ooz Bash (オーズバッシュ, Ōzu Basshu).

Ride Vender
The Ride Vender (ライドベンダー, Raido Bendā) is Ooz's personal Honda Faze Type S. It is named for its transformation from a vending machine mode which also holds Ooz's Candroid support robots. It can also combine with the Tora Can Droid to become the Toride Vender (トライドベンダー, Toraido Bendā).

Can Droids
The Candroids (カンドロイド, Kandoroido) are special support robots that are held within the Ride Vendor. After inserting a Cell Medal into the Ride Vendor in its vending machine mode, a beverage can like device is "bought" from the machine. The Candroid is transformed from its Can Mode (カンモード, Kan Mōdo) into its larger Animal Mode (アニマルモード, Animaru Mōdo) through the pull-tab on top.
 * The Taka Can Droid (タカカンドロイド, Taka Kan Doroido) is a Can Droid "bought" with the Taka Cell Medal. It's Animal Mode has the ability of flight.
 * The Tako Can Droid (タコカンドロイド, Tako Kan Doroido) is a Can Droid "bought" with the Tako Cell Medal. It's Animal Mode has the ability of spinning it's tentacles aroun and swim under water.
 * The Batta Can Droid (バッタカンドロイド, Batta Kan Doroido) is a Can Droid "bought" with the Batta Cell Medal. It's Animal Mode has the ability of hopping to long distances and shoot medals.
 * The Denki Unagi Can Droid (電気ウナギカンドロイド, Denki Unagi Kan Doroido) is a Can Droid "bought" with the Denki Unagi Cell Medal. It's Animal Mode has the ability to create electricity in it's head and swim under water.
 * The Tora Can Droid (トラカンドロイド, Tora Kan Doroido) is a Can Droid "bought" with the Tora Cell Medal. It's Animal Mode has the ability to launch two Cell Medals (Tora and Cheetah) from it's claw. It can also combine with the Ride Vender.