A cataclysmic event involving an artifact of an ancient Martian civilization has created a supernatural barrier called the Skywall which separates Japan into three territories, Touto, Hokuto, and Seito.

Along with creating a complex power dynamic between the three regions, the event brings waves of monsters called Smash down on the country, who terrorize and attack the citizens.

Build has different powers determined by the combination of a pair of Fullbottles inserted into the belt, each containing the essences of organic and inorganic matters.

Throughout the story, Sento learns that his forgotten past is connected to the events of the Skywall Catastrophe, that the Smash is the work of a larger organization attempting to rule the world, and that his allies are not what they seem.

[2] A press conference was later held on August 1, 2017 to reveal the cast and crew, plot details, the suit and bike of Kamen Rider Build.

A Movie War film, titled Kamen Rider Heisei Generations Final: Build & Ex-Aid with Legend Rider (仮面ライダー平成ジェネレーションズ FINAL ビルド&エグゼイドwithレジェンドライダー, Kamen Raidā Heisei Jenerēshonzu Fainaru Birudo Ando Eguzeido Wizu Rejendo Raidā) was released on December 9, 2017.

It also featured a cameo appearance of Build's titular successor, Kamen Rider Zi-O, before his proper debut in his own series.