Idea for Kamen Rider anniversary season
An alien civilization intends to harvest the earth's resources by using their shapeshifting ability to infiltrate human societies to start wars to increase their chances of success in enslaving humanity
Prolonged periods of remaining in a shape unnatural to the aliens causes their bodies to break down, so they developed a device to stabilize their transformations by using dna samples from the target population, with a simplified version for the footsoldiers, and more complex versions for those higher in the rankings
During the start of an invasion, Footsoldiers are typically sent in groups of up to 5 in order to lower chances of suspicion, with the goal of replacing people deemed to have higher quality genetics for experiments
During the second stage of invasion, sleeper agents are sent into areas with more hospitality, with the goal of sabotaging technological development via replacing it with technology that can effectively shut down nearby defenses
Sleeper Agents are periodically informed to take a specialized medication to reset their minds in order to keep them from becoming too attached to their assigned community and becoming rebellious
However, at least one sleeper agent has developed a sort of Pseudo-immunity to the medication and stolen both an experimental stabilization device in the shape of a belt, as well as a set of dna samples from genetic outliers, such as people with strange abilities and modified bodies
This rogue individual has begun to interfere with other communities assigned infiltrators in an attempt to stop this invasion and has labeled themselves as a "Kamen Rider", an individual who protects the earth's population