舞台是TV系列最終話的之後。
戰兔產生出的「新世界」裡的故事。 桐生戰兔創造了新世界。
當中的人們,失去了一切與假面騎士及Sky Wall有關的記憶,和平地生活著。戰兔與搭檔・萬丈龍我在記錄之前的世界所發生的事情同時,一邊以販賣戰兔的發明品過活。 某一天,龍我與擁有假面騎士Cross-Z的記憶的神秘少女・馬渕由衣相遇。由衣說自己在之前的世界裡,被Cross-Z離棄成為了人體實驗的受害者,責備龍我。 與此同時,自稱“Killbas”的神秘地球外生命體突然從白色潘多拉嵌板裡出現,襲擊戰兔。Evolto的兄長,曾是Blood族之王的Killbas擬態成傳奇舞者・柿崎悟志的外貌。更襲擊龍我與由衣,縱使應戰在Killbas壓倒性的力量面前也陷入了危機。
但是,那一瞬間,有誰保護了龍我。而那真身就是――Evolto。 讓潘多拉盒子完全復活,以其力量企圖毀滅整個宇宙的Killbas。以潘多拉盒子的力量,昔日的同伴們取回記憶,於龍我的身邊集合。龍我與Evolto組成奇妙的搭檔,對抗Killbas威脅…!?到底龍我能夠拯救宇宙,以及拯救由衣?並且,Evolto真正的目的是什麼…?
When Amanda and friends stumble across an old boat, they think they have found an ideal secluded party spot. Drinking too much and cranking up their music they have no idea that they are disturbing the boats violent sole occupant- a scarred figure with a painful past and a dark secret. Soon this mysterious violent man begins to pick off the unwelcome visitors and adds them to his macabre collection in the meat locker. Amanda thinks help is at hand with the arrival of another group on board but the newcomers have their own agenda and wont let anything get in their way.