Eiji Hino is a wanderer who has no place to call home and a tragic past. When metallic creatures known as the Greeed awaken after their 800-year slumber to attack humans and feed off of their desires, the disembodied arm of the Greeed named Ankh gives Eiji a belt and three Medals to fight the other Greeed as Kamen Rider OOO. The mysterious Kougami Foundation approaches Eiji and begins assisting him in his fight against the Greeed, though their true motives are not clear. As Eiji fights the Greeed and their Yummy monsters, learning more about the Greeed and Ankh, he starts to find a purpose beyond his journey.
Medals, Underwear, and a Mysterious Arm (Episode 1)
Writer: Yasuko Kobayashi
Air date: 2010-09-05
Runtime: 23 min
Overview: A mysterious arm reawakens the Greeed from their slumber and decides to use Eiji Hino, a cheerful wanderer, as his means of getting back what he desires as Kamen Rider OOO.
Desire, Ice Pops, and Presents (Episode 2)
Air date: 2010-09-12
Overview: Ankh explains the Greeed and the purpose of the Medals to Eiji, even as the human desires to merely use his new power to fight for good instead of for selfish needs.
A Cat, Evolution, and a Glutton (Episode 3)
Air date: 2010-09-19
Overview: Ankh becomes troubled when Eiji prevents him from eliminating his possessed body's sister while another Greeed uses a man's gluttony to create more Medals.
Doubt, a Picture Message, and a Helping Hand (Episode 4)
Writer: Yasuko Kobayashi
Air date: 2010-09-26
Overview: Ankh threatens to leave OOO for Kazari and the Greeed while investigating the evolution of humanity while Eiji tries to find more about Hina.
A Game of Tag, a Nest, and a Rich Girl (Episode 5)
Air date: 2010-10-03
Overview: Kougami asks for a share of Eiji and Ankh's Medals, while Mezool decides to use Hina's shopaholic classmate to create a new Yummy.
Fashion, a Contract, and the Strongest Combo (Episode 6)
Air date: 2010-10-10
Overview: Hina confronts Yamano's shopping addiction when her father goes bankrupt while Ankh confronts Kougami about his share deal of the Cell Medals.
A Lousy Husband, a Trap, and a Jackpot (Episode 7)
Air date: 2010-10-17
Overview: Eiji tries to research a husband bullied by his wife that is being mocked by Gamel while Ankh follows a lead for a missing Core Medal.
Sabotage, Having No Greed, and Taking a Break (Episode 8)
Air date: 2010-10-24
Overview: Amidst Hino's failed attempts at stopping the Komoris' argument, Momoko takes the winning scratchcard and throws it into a nearby river. As Takeshi frantically searches for it, she reveals to Hino why Takeshi has become so greedy.
Drenched, the Past, and the Scorching Combo (Episode 9)
Air date: 2010-10-31
Overview: In flashbacks, Eiji fails to save a girl amidst a foreign civil war. In the present, Satonaka meets with Eiji to collect Kougami's fee until an explosion occurs outside.
A Fist, an Experiment, and a Super Bike (Episode 10)
Air date: 2010-11-07
Overview: As Maki observes the bomber, Kougami Biotech Laboratory technician Toru Tadano, Ankh scolds Eiji, who later discovers Maki's whereabouts.
A Traveler, a Swallowtail, and a Celebrity (Episode 11)
Air date: 2010-11-14
Overview: Eiji encounters an old friend and globetrotting blogger, Keisuke Tsukuba, who has come to Japan to find a publisher for his work.
An Eel, the World, and the Gravity Combo (Episode 12)
Air date: 2010-11-21
Overview: Following Goto's attack, the Ageha Yummy retreats again while Eiji learns of Goto's distate towards him.
