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」, Imajin Anime Momotarosu yo Eien ni -Imajin Shūchakueki-/Gekijōban?) was shown as a 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 (although some feel uncomfort to their new surrounding) . 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, Momotarosu yo Towa ni ~Imajin Shūchakueki?), provides an alternate ending where the story does continue with numerous new characters and Momotaros freaks out about it.
Read more about this topic: Saraba Kamen Rider Den-O: Final Countdown