Amazon Riders(仮面ライダーアマゾンズ)

The series revolves around a race of genetically-engineered mutants known as Amazons, around four thousand of which are set loose into a city after a mysterious lab accident. Though normally able to mimic humans and live peaceful lives, the Amazons transform into ravenous flesh-eating monsters when the medicinal suppressant within their armlets runs out after two to three years.