Kamen Rider: Arrival

In the universe, two planets that appeared out of nowhere collided with each other, and the light ball produced by the explosion came to the earth... The story of the duel between the Armor Warrior and the Kamen Rider, and how they practiced together to fight against alien creatures. (Kamen Rider fanfic, don't pay attention to the settings in some places, the name Cancer is directly copied from Kamen Rider)