続ける! 仮面ライダー!

51 years ago, before the original Kamen Riders were created, Ryu Katsuri was supposed to be used as the original Kamen Rider, but Shocker's plans changed after Hongo escaped.

Before he could be awakened, the Double Riders destroyed the Shocker base and the sleep capsule that Katsuri was in was buried underneath the rubble of the Shocker base for 51 years.

When he finally awakens in the present day, Katsuri has no recollection of his life. The story follows his quest to regain his memory and figure out who turned him into a cyborg.