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.
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.
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.
Ankh threatens to leave OOO for Kazari and the Greeed while investigating the evolution of humanity while Eiji tries to find more about Hina.
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.
Hina confronts Yamano's shopping addiction when her father goes bankrupt while Ankh confronts Kougami about his share deal of the Cell Medals.
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.
Eiji gets to the root of the Komoris' problem involving greed and loss of ambition while Ankh fights for survival after a failed confrontation with Uva.
A serial bomber tied to a nest of Yummies leads to Eiji to reveal his past to Hina and forces him to encounter a strange man he believes is Mezool's victim.
Eiji must figure the means of stopping the mad bomber and his Yummies to prevent any more lost lives, even with Maki observing the creation of his worker's monsters.
Eiji's traveler friend becomes manipulated by Uva into becoming famous as he steals others attributes; while Gotou doubts Eiji's effectiveness as OOO.
Eiji teaches a lesson to Tsukuba and Gotou about going forth to gain what is desired; while Ankh tries to figure a way to manage the flying Ageha Yummy using Gamel.
Ankh is at a breaking point with everything surrounding his human host; a highly sought after doctor has been repeatedly removed from the operating room, making her frustration a perfect target for the Greeed.
Both Hina's brother and the hospital director are in critical condition after Ankh's detachment and the Yummy attack. Eiji must find both Ankh and the affected surgeon before it's too late.
Ankh finds one of his core medals; Gotou is transporting a truck full of medals to Doctor Maki; Kazari appears to Ankh and Eiji, telling them that Hina is in Gotou's truck.
Eiji learns about how the Greeed were born; Gamel searches for Mezool; Kamen Rider Birth joins the fight.
The Greeed take an interest in a girl who wants to get better at kendo; Ankh takes an interest in Kamen Rider Birth; Hina gives both Eiji and Ankh gifts for saving her.
Eiji and Ankh try to find out the reason that the Yummy split in two, but Kamen Rider Birth is one step ahead of them.
Kougami tries to give Eiji one of Ankh's medals, but he refuses; a face from the detective's past shows up at Cous Coussier; thanks to Kazari, a criminal that the detective put away is on the streets and looking for revenge.
Ankh tricks Kazari by telling him that Eiji knows where his last medal is and then chases after Hina who has his own medal; Date and Gotou discuss the skills need to be Kamen Rider Birth; Kougami changes his mind and sends Ankh's medal to Eiji.
The Cous Coussier gang runs into a young boy getting attacked for telling off a man for littering, learning that it's something he picked up from his father; the Greeed creates a Yummy from the desire to help people.
Susumu lets his desire for justice get out of hand and it's up to Eiji to stop him before it's too late; Gotou and Takashi have a heart-to-heart conversation about their ideals.
Kazari is drawn to the vanity of woman whose sister takes all the credit for her work.
Eiji is head over heels for Yuumi and it's up to Date to save his old friend before she does something that she'll regret.
Ankh is acting more standoffish than usual; a boxer is forced into retirement just before a big match and is captured by a bird Yummy.
Eiji is still super beat up from the previous battle but he is the only one who believes that Ankh did not create the bird Yummy; Kazuki heads back to the ring as Date and Gotou rush to stop him from injuring himself more.
Kougami invites Eiji and Ankh over to celebrate the 1000th episode of Kamen Rider and decides to make a movie to celebrate; Kazari is drawn to a Shocker grunt who joins the movie.
Even though he's injured, Date still wants to finish directing the movie; Sendou starts sabotaging the movie with his new friends.
Kazari uses Dr. Maki's desire to make a Yummy; Gotou goes back to work; a strange monster shows up with Ankh's other arm.
Dr. Maki and Chiyoko have a heart-to-heart talk about his sister; Kazari takes Ankh's memoryless body under his wing; Kougami tells Gotou the story of the medals as Eiji and Date get Ankh to finally tell his story.