After the end of the civil war that tore apart Japan, the new governors of Touto, Hokuto and Seito work together to reunify the country. However, they are actually members of an extraterrestrial race called the "Blood Tribe" (the same species as Evolto), who assumed their government positions as part of a plan to destroy Earth as they have done to Mars and other planets before. Considering Sento Kiryū (Kamen Rider Build) a major threat to their plans, the Blood Tribe manipulates his friends and other civilians into attacking him. With even his close ally Ryūga Banjō (Kamen Rider Cross-Z) now against him, Sento must fight to survive and stop the Blood Tribe's plan from succeeding.
犬飼貴丈
as Sento Kiryuu · Kamen Rider Build
赤楚衛二
as Ryuuga Banjou · Kamen Rider Cross-Z
高田夏帆
as Misora Isurugi
武田航平
as Kazumi Sawatari · Kamen Rider Grease
越智友己
as Nariaki Utsumi
小久保丈二
as Shinobu Katsuragi
木山廉彬
as Takumi Katsuragi
藤井隆
as Mitsuomi Goubara · Zebra Lost Smash
松井玲奈
as Ryouka Saiga · Scissors Lost Smash
奥野壮
as Kamen Rider Zi-O (voice) (uncredited)
金尾哲夫
as Evolto / Kamen Rider Evol (voice)
Koharu Tanahashi
as Yuu Maihara
