Eighteen year old orphan Kit Taylor is drawn into a dangerous and secret war occurring on Earth when his missing father contacts him through a mirror, instructing Kit to "search for the dragon". Upon discovering a deck of cards in his apartment, Kit is attacked by armored warriors. Kit's bid to escape lures in attractive reporter Maya Young, and gains the attention of the arrogant Wing Knight, who, though opposed to the forces pursuing Kit, also craves the cards, known as Advent Decks, that Kit is in possession of....
Kit is advised by his father to "contract with the dragon" using a contract card stored within his Advent Deck. The contract merges Kit and the pursuing dragon, transforming Kit into a Kamen Rider. Wing-Knight, incensed with this, takes his leave. Kit unites with reporter Maya Young to investigate his father's disappearance as well as the paranormal activity present in the city.
Kit faces off against a fellow Kamen Rider, Incisor, a spoiled teenage millionaire manipulated by Xaviax. During the battle, Wing Knight comes to Kit's aid, and agrees to teach him more about his powers now that he is facing considerably greater obstacles
While talking with Len, Kit discovers that the Kamen Riders were the defenders of the mirror world of Ventara. The mysterious Advent Decks were actually stolen from the Riders and given to certain people on Earth. Then, Len challenges Richie to a battle and ends up sending him to the Advent Void, where he will be trapped forever. Realizing how dangerous these battles are, Kit quits being a Kamen Rider.
The evil alien Xaviax concocts a plan to harvest human DNA to transport humans to his home world. Once transported there, the humans will be turned into slaves. Unfortunately, Kit is still reluctant about becoming a Kamen Rider and Len needs to set him straight. Once Kit learns of Xaviax's plan, he decides that he's ready to become a Kamen Rider and save the world.