Deputy Officer of the United Nations Alliance, Simon Marcus, who aims to conquer the world with the terrorist organization Downfall together with the mad scientist Keiji Uraga, assault the Kamen Riders with overwhelming strength. It is simplest on Kamen Rider Grease that the enemy's abilties did now not work. In order to defeat this new enemy and rescue Misora, Kazumi Sawatari must create a new object ... But it is told that it calls for the existence of his friends, the Three Crows. The ultimate choice should be made.