"Mirror World" exists symmetrically beyond an invisible mirror in space and is an exact copy of our human world where only monsters can dwell. Evil monsters frequently cross the mirror and attack our world. Only Kamen Riders who make a contract with a specific monster and obtain a special power from it can enter "Mirror World" to fight with the help of an "Advent Card." Shinji Kido a journalist contracts with a dragon and becomes Kamen Rider Ryuki. He fights a fierce battle with evil monsters. Many Kamen Riders appear one after another and fight to satisfy their own aims. However only one Kamen Rider can outlive the others. Thus it is their fate to keep fighting to the last man.