The Underground Empire Badan makes its move, intending to invert the world. Kouta and Mai are pulled through one of these inversions where the discover a boy named Shu, who also holds the power to invert the world. As the Riders fight to protect Shu, Fifteen appears again, seeking Shu. As Kouta flees, past Riders gather and fight one another, split between the Showa and Heisei era Riders. But, the truth of Badan is not as it seems…
佐野岳
as Kouta Kazuraba / Kamen Rider Gaim
藤岡弘、
as Takeshi Hongo / Kamen Rider #1
板尾創路
as Ren Aoi / Kamen Rider Fifteen
井上正大
as Tsukasa Kadoya / Kamen Rider Decade
半田健人
as Takumi Inui / Kamen Rider Faiz, Riderman (voice)
桐山漣
as Shotaro Hidari / Kamen Rider Joker / Kamen Rider Double
小林豊
as Kaito Kumon / Kamen Rider Baron
高杉真宙
as Mitsuzane Kureshima / Kamen Rider Ryugen
久保田悠来
as Takatora Kureshima / Kamen Rider Zangetsu Shin, Shin (voice)
志田友美
as Mai Takatsukasa
弓削智久
as Kiyojiro Bando
那月結衣
as Iyo
