A Kamen Rider Zero-One spin-off centered around Gai Amatsu, AKA Kamen Rider Thouser has been announced.
Project Thouser will focus on the origins and mystery of ZAIA president Gai Amatsu, AKA Kamen Rider Thouser. The spin-off will be a bonus video that is to be released with the Kamen Rider Zero One Blu-ray Collection. Project Thouser will be directed by Shojiro Nakazawa. Additionally, the screenplay will be written by Minato Takano.
More information about the spin-off will be released at a later date.
Source: Toei Video