Finale: The Medals of Tomorrow, Underwear, and Arms Held

As Shintaro and Date are powerless against the complete Uva, they notice a massive explosion nearby. Emerging from the Kougami Foundation, with the weight of a million Cell Medals inside him, Eiji arrives as Kougami meets with Maki above the battlefield. With the King's Core Medals, three of the tenth Core Medals from each set, Eiji becomes Kamen Rider OOO and easily defeats Uva with both the Medajaribur and the Medagabryu. However, refusing to accept Kougami's ideals, Maki intervenes and installs the other Core Medals into Uva against his will. Kamen Rider OOO attempts to stop Maki, but is powerless, just as Ankh arrives to his aid. Uva attempts to flee with Maki in pursuit as Ankh restores his friendship with Eiji. However, the purple Core Medals inside Kamen Rider OOO force Eiji to revert while destroying the King's Medals. Later that night, Ankh tells Hina not to tell Eiji that he is dying, but she feels conflicted about his request as well as Eiji's worsening condition. The next day, as Chiyoko finds Kiyo-chan dressed up as Maki in her restaurant, Uva turns into the out of control Medal Vessel that proceeds to create an army of Waste Yummy out of the matter it consumes. Kougami bakes a birthday cake amidst the chaos, while Kamen Riders Birth and Birth Prototype, along with Satonaka deal with the Waste Yummy and Kamen Rider OOO Putotyra Combo and Ankh battle Maki. When Eiji's risky Grand of Rage attack using the Cell Medals he has absorbed fails to defeat the Kyouryu Greeed, Eiji prepares to assume his Greeed form when Ankh intervenes by throwing him his Core Medals. Realizing that Ankh is sacrificing his final moments to save him, with Ankh now fighting by his side in spirit, Eiji becomes Kamen Rider OOO Tajadol Combo and defeats Maki using a purple Core Medal powered Giga Scan. But this causes a black hole to emerge from within the Kyouryu Greeed, sucking him in along with all the Core Medals before the Medal Vessel explodes. Falling to his death while unconscious, Eiji is awakened by Ankh as the Greeed sees that Eiji knows he is about to die and bids his goodbyes, leaving only half of the Taka Medal that once contained his consciousness. Shintaro, as Kamen Rider Birth, manages to save Eiji by catching him midair with the Cutter Wings installed. Upon seeing his friends below, Eiji realizes he has achieved his desire to reach others. Soon after, with Hina giving him the other half of Ankh's Taka Medal that she found through a similar manifestation of their fallen friend, Eiji decides to leave Japan and resume his worldly travels.

Sometime later, everyone returns to their previous lives. Shingo and Shintaro return to the police force, and one day as Hina goes to fashion school, they pass by two high school students, one of whom is carrying a strange switch-like device. Akira Date begins work as a relief doctor. Kougami continues to have Erika Satonaka in his employ as he bakes more birthday cakes. One day, everyone visits the Cous Coussier and Chiyoko serves them a cake before revealing an iPad with Eiji on screen somewhere in a desert, using an iPhone to call them with FaceTime and update them on his journeys. Before he leaves to his next destination, a fresh pair of underwear in tow, he looks at the broken Taka Medal and promises to find a way to fix it, seemingly unaware of the spectral Ankh arm following him. [48] 