- Title: Kamen Rider OOO Wonderful : The Shogun and the 21 Core Medals
- Alternative Title: 劇場版 仮面ライダーオーズ WONDERFUL 将軍と21のコアメダル Gekijōban Kamen Raidā Ōzu Wandafuru Shōgun to Nijū-ichi no Koa Medaru
- Number of Episode: 1
- More Info: https://en.wikipedia.org/wiki/Kamen_Rider_OOO_Wonderful:_The_Shogun_and_the_21_Core_Medals
- Summary: Leading an expedition in Thuringia, Germany, Kousei Kougami was unearthing the resting place of one of the First OOO's alchemist to obtain legendary Lost Medals. However, upon the seal being undone, millions of Cell Medals erupt into a tower while creating a magical barrier that causes it the entire sit to flip over to Japan. This attracts Eiji Hino's attention as he and Ankh investigate. Arriving as Knights emerge from the tower after it dragged Kougami and Erika Satonaka in, Akira Date arrives as Eiji and him become Kamen Riders OOO and Birth to battle the Knights. The fight eventually attracts the other Greeds' attention before a new figure arrives and takes the Core Medals from all sides. Attempting to kill a boy that Kamen Rider OOO saves, the figure revealing his intent to become the New OOO of a new world before taking the Taka Medal and forcing everyone out with a barrier set up. Taking the boy to the Cous Coussier and learning his name to be Shun Wakaba, Eiji asks the boy why he was there before Shintaro Goto reveals their enemy to be known as Gara, one of the alchemists who created the Core Medals. Following Ankh when he senses something like Gara, Eiji and company find a strange girl called Belle as she presents 5 million yen to obtain Cell Medals from those she tricks so Gara can use the weight of human desire to execute his doomsday plan.
Once enough Cell Medals are gathered, Gara's magic device activates with Date and Shintaro watching Eiji and the others end up in the Edo era where he attempts to keep the peace between the present and past peoples. But without warning, the Nue Yummy appears and attacks Eiji. Unable to become OOO, Eiji uses the Birth Driver to become Kamen Rider Birth to fight the Nue Yummy before he takes Ankh's Kujaku and Condor Medals and takes his leave. Though the fight caused the past people to demonize Eiji and others, Tokugawa Yoshimune manages to calm everyone down. Back in the present as another area of Japan flipped over for the Mezoanic Era, Kougami talks Gara into going after Eiji to use his desire to speed up the doomsday countdown. Later that night in Edo Japan, Eiji learns from Shun that his mother, Satsuki, was taken earlier when the tower appeared and become a vessel for Gara's soul while assuring the boy that his mother loves him.
The next day, forced to use Ankh's main Taka Medal, Eiji becomes Kamen Rider OOO to fight the Nue Yummy and his platoon of Knights with Hina backing him up. Things seemed hopeless until Tokuda arrives to Kamen Rider OOO's aid along with the Edo residents. Once the Knights are dealt with, Yoshimune gives Kamen Rider OOO a set of Core Medals belong to the Tokugawa family. Using them, OOO becomes Kamen Rider OOO Burakawani Combo to destroy the Nue Yummy. As Yoshimune takes his leave, Belle arrives to offer Eiji the choice to return to his time with everyone else fading from existence. Though agreeing on the condition that he brings his "family", Eiji manages to trick Belle into saving everyone. As a shocked Belle explodes, Eiji's infinite desire overloads Gara's device to the alchemist's horror as Eiji and friends return to their time.
After Eiji finds a Taka Medal stuck to his shoe, Eiji becomes Kamen Rider OOO and enters Gara's tower as Shintaro and Date destroy the barrier. Kamen Rider OOO vows to free Satsuki from his hold, Gara assumes his true form and takes their fight outside while Satonaka gets Kougami to safety. Shun's presence enables OOO to save the boy's mother as an enraged Gara almost kills the Kamen Rider before the sudden arrival of Kamen Rider Fourze. With Fourze declaring Kamen Rider OOO a friend, the two Kamen Riders double team Gara and knock him into his tower. Negating his transformation, Gentaro Kisaragi gives Kamen Rider OOO his handshake before running off to Amanogawa High School. However, managing to take Eiji's purple Core Medals to complete the seven sets of Core Medals in his possession, Gara absorbs them to become Gara Dragon. Kamen Riders OOO and Birth are powerless against Gara until the Greeed arrive and Uva gives the former his Core Medals so he can assume Gatakiriba Combo. Then receiving more Core Medals from the Greeed, each Gatakiriba clone changes into Kamen Rider OOO's seven other Combo forms. With Birth's Breast Cannon, the eight OOOs use their Scanning Charges in synch to destroy Gara with the area raining Cell Medals. As Shun and Satsuki take their leave, Eiji talks Ankh into holding Hina's hand as she holds his hand as well. Remembering what he said, Eiji realizes that he, Hina, and Ankh are a family as they all walk home.