Ten years ago, a blood-red rift suddenly tore open the sky, and monsters known as the Yimo descended upon the world, bringing disaster in their wake. To face the crisis, humanity used the Yimo's power to create Spirit Keys, gradually wiping them out. But the rift still hangs in the sky... Years later, the revived Yimo launch another attack. A young man and woman transform into Kamen Rider stand-ins and fight back, only to gradually discover the cruel truth about the world...
