One day, Flash wakes up out of the blue to find himself in possession of an unusual device and no memory of how he got it. And when his home is invaded by shape-shifting monsters, he finds he will need to use that device to save his friends and family.

With the powers he now possesses, Flash must take on the mantle of hero. Along the way, he will face many challenges and uncover many secrets. He may end up sacrificing everything in order to protect his world, but he will grow stronger through those sacrifices. And eventually, he may learn to live up to the title given to him. The title of a Kamen Rider.