Farewell Kamen Rider Electric King: The Final Countdown

Plot
Taking place after the events of series, the Tarōs and Kohana go out of the Den-Liner for a day to visit Ryotaro and Airi. However, they see the mysterious Ghost Train that has been mentioned in urban legends as Momotaros and gang are then attacked by two evil Imagin and Kamen Rider Yuuki Skull Form. During the fight, it is revealed to the Tarōs that Yuuki is none other than Ryotaro possessed by an evil Imagin. Even with Kamen Rider Zeronos coming to the gang's aid, things seem bleak until a blue DenLiner appears with a new figure: Kamen Rider New Den-O. After destroying the Shadow Imagin, with Yuuki and the Phantom Imagin retreating to the Ghost Train, the gang is brought onto the New DenLiner. There, Owner formally introduces the new Rider as Kotaro Nogami, Ryotaro's grandson from the future, and his Imagin Teddy. After Owner reveals he summoned Kotaro in respose to a threat posed by the Ghost Train and its owner Shiro, who seeks to use the Ghost Train to reverse the worlds of the living and the dead. After Kotaro explains to Momotaros that intends to pick up the slack for his grandfather, whom he has no respect for, he goes after the Ghost Train by himself as New Den-O to fight Yuuki after killing the Phantom Imagin until Shiro arrives and defeats New Den-O personally. Yuuki is about to kill Kotaro when Ryotaro attempts to regain control over his actions as the Taros arrive. Although Shiro and Yuuki escape, the New DenLiner crew get a Rider Ticket and a partial message from Ryotaro to Momotaros about protecting an "elephant" that leads them to where Shiro intends to carry out his plan: May 23, 1729.

There, the New DenLiner gang learn they have reinforcements in both Sieg and then Deneb, who joins up with the gang in Yuto's stead as he is still injured from the fight with Yuuki. After looking for clues, encountering people who resemble Airi, Ozaki, and Miura, and unable to find any elephant except a traditional drawing of one in the middle of the town taken from a future point in time, the rest of the group questions whether or not Momotaros heard things right. During their dinner, Kotaro takes his leave as Momotaros follows him in an attempt to talk to him about how he strong is like his grandfather, but Kotaro has yet to see his grandfather in any way resembling someone "strong". Later that night, Teddy discovers Shiro's plan to kill everyone in the village the next day, but is found out and attacked. He struggles back to their base of operations so his friends will know and says how the "elephant" is not really an elephant. Although New Den-O is without his partner and Yuto is still injured, Momotaros decides to get Ryotaro back even if it is the last thing he does. The next day, the other Tarōs and Deneb battle the mercenaries as Momotaros fights his way to Yuuki, attempting to call out of Ryotaro to fight his possessor before getting a mortal wound from Yuuki to his friends' horror. But at the last second, Ryotaro regains control as Momotaros enters his body and drives the Ghost Imagin out of him. Assuming Climax Form, Den-O easily takes out the Ghost Imagin as Shiro takes the Yuuki Belt and assumes Yuuki Hijack Form as he uses his necromancy to summon every Imagin the Riders have ever faced back from the dead.

After Climax Form is defeated, a fully healed Yuto and Kohana arrive via the ZeroLiner and New DenLiner, with Kohana giving the Tarōs and Sieg their own Rider Passes. The Imagin each assume their Den-O forms as Ryotaro becomes Liner Form and Yuto becomes Zero Form. While the others battle the Imagin, Liner Form, Sword Form, and later New Den-O pursue Yuuki on horseback. Together, the three Den-O's mortally wound Yuuki who reverts back to Shiro. Sora arrives, revealing to everyone else that she had been dead for 400 years and did not wish to be alive again, only to be with Shiro for eternity. Accepting his fate, Shiro and Sora board the Ghost Train to be together forever in the realm of the dead. When the New DenLiner arrives in the middle of town to pick up the gang, Naomi questions being out in the open while Owner reveals that the locals will only recognize it as an elephant. Ryotaro also reveals that he was aware of the "elephant" as it was the point in time where his ancestor Oyuki finds her true love. It is this point in history that Shiro planned to negate, preventing Ryotaro from ever existing and allowing him to bring Sora and everyone else who had died back to life. With his mission complete, Kotaro gains a new respect for his grandfather as he and Teddy are brought back to their time via the DenLiner, where they meet up with the elderly Ryotaro of their future.

New DenLiner Crew

 * Owner
 * Maggie
 * Justina

Milk Dipper

 * Amanda Winfield
 * Izzy Bayman
 * Justice Snyder

Others

 * Sora

Momotaros Forever!
The animated short Imagin Anime: Momotaros Forever! -Imagin Terminal Station-/The Movie (イマジンあにめ「モモタロスよ永遠に－イマジン終着駅－／劇場版」) was shown as double feature. In the short, Momotaros feels bad that it is really the end of Kamen Rider Den-O as Urataros assures him that all good stories have to end sometime. After Kintaros and Ryutaros try to make sequels to classic stories that cannot have a sequel, the Imagin end up on the moon in homage to Galaxy Express 999, embracing their final story. But a later retelling of this short, Be Forever Momotaros: Imagin Terminal Station (モモタロスよ永遠に　～イマジン終着駅), provides an alternate ending where the story does continue with numerous new characters and Momotaros freaks out about it.