This article is about a/an alternate reality/A.R. World (another rider's world) in Kamen Rider Build.
World of Build

World of Build

A nation divided

Japan in World of Build

The World of Build (ビルドの世界 Birudo no Sekai), alternatively refered as World A, was an A.R. World home to Sento Kiryu and the reality which Kamen Rider Build takes place. As a result of Evolto's subsequent attempt to destroy the Earth, Japan was divided into three regions by the Sky Wall, while his work to regain the power he lost ultimately resulted in the creation of the eponymous Kamen Rider Build.

Worlds collide..literally

The World of Build begins to merge with a parallel world

It was ultimately merged with another Earth without the Sky Wall, which was coined by Sento as World B, and the resulting world dubbed the "New World". People who died in one of the worlds were simply replaced with their parallel versions, although those that died as a result of the Lost Bottle experiments now carried scars or were rendered comatose. If a person was alive on both worlds, both versions were merged, with the exception of Sento, who exists only because of Evolto's manipulation. Similarly, Ryuga merged with a part of Evolto before birth, allowing him to exist alongside his alternate version.

Upon the appearance of Killbus and the activation of the Pandora Box via the White Panel, the memories of those who were experimented on by Faust, including Misora, Sawa, Kazumi, Gentoku, and Yui, were restored to their alternate selves, and Evolto was resurrected.


Sky Wall Disaster

Main article: Sky Wall Disaster

In the year 2008, the Sky Wall Disaster caused by the activation of the Pandora Box resulted in Japan being split into Touto, Seito and Hokuto, which would then cause the beginnings of the Japanese Civil War.


On November 30th, Sento and Ryuga were neutralizing a Strong Smash Hazard when they rescued a mysterious young man named Sougo Tokiwa, who claimed to hail from one year into the future. Taking him with them back to nascita, Sento examined the Ridewatch on Sougo's person, confirming through its technology that it did indeed hail from a future time period as Sougo had claimed. Soon after, Tsukuyomi entered nascita, using her Faiz Phone X to stun all three men before returning Sougo to his own time. Kingdom 2068


Main article: Japanese Civil War



Main article: Human








Behind the scenes

As established from the first episode, the Sky Wall Disaster of ten years prior had extreme effects on Japan which were not present in prior Kamen Rider Series. Ultimately, the film Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders confirmed that Kamen Rider Build took place in its own world separate from the World of Ex-Aid, home to Ex-Aid as well as the various Legend Riders such as Ghost, Gaim, Fourze and OOO.


World of Build Country

World of Build country in the Korean dub.

  • In the South Korean dub of Kamen Rider Build, the country was changed from Japan to a fictitious country due to political reasons.



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