|This article is about a/an location in Kamen Rider Zi-O.|
Within the Multiverse, Another Decade has the ability to access several Another Worlds (アナザーワールド Anazāwārudo), which are alternate versions of reality in which past events are altered based on the regrets of their prime universe selves, like how Sougo Tokiwa's classmate Nishimura lost a race in the real world, but won it within the personal reality of the Another World. Events in these Another Worlds loop forever.
As a side effect, a dark Rider will be revived with the creation of an Another World. Like the victims themselves used to create the worlds, the revived Riders will also be stuck in a loop of their defeated battle in the past, but with inverted results. An example is that Katsumi Daido lost to Kamen Rider Double in the real world, but won instead in his Another World. Using a loop effect, Swartz can summon the dark Riders again after their defeat in the real world, although the number of times he can do this is questionable.
- Shiro Mizuki (Kamen Rider G4) - From an unknown world
- Takato Shiramine (Kamen Rider Rey) - From an unknown world
- Argos (Kamen Rider Dark Ghost) - From an unknown world
- Kagenari Nagumo (Kamen Rider Fuma) - From an unknown world
- Paradox Roidmude (Kamen Rider Dark Drive & Another Drive) - From an unknown world
- Katsumi Daido (Kamen Rider Eternal) - From the Another World of Takashi Owada, who regretted losing the gaming tournament.
- White Woz (Kamen Rider Woz) - From the Another World of Geiz Myokoin, who regretted not confessing his true feelings to Sougo.
- Shiro (Kamen Rider Yuuki) - From the Another World of Yukihiro Osumi, who regretted the loss of his girlfriend's life.
- 3 other unknown dark Riders - From the Another World of the other 3 victims shown in episode 46.
- Kamen Rider Zi-O
- The idea of a world where alternate/altered versions of past mainstream events exist is similar to the concept of Marvel's "What If...?" series of comics, which explored what would happen in the Marvel Universe should certain moments in said universe have not occurred as they did in the prime timeline.
- https://www.tv-asahi.co.jp/zi-o/enemy/another_decade/ in 07/21/2019.