An aerial war that challenges the ancient King. The strongest parent-child Rider in history attacks a giant Rider.

When a powerful new foe known as the Legendorga arises in 2008, Wataru investigates the mystery behind the crisis, which brings him in contact with a man Nago once knew, Shiramine Takato, whose 3WA also possess their own Rider System. When Shiramine explains how everything began in 1986, Wataru uses Castle Doran’s Time Door to travel back in time, leading him to meet his father face-to-face at last. But has Wataru managed to change the future, or will the Legendorga still rise and enslave humanity?