Along with other Riders with mysterious origins, Tendo Soji under his Kamen Rider Kabuto identity tries to protect the girl Kusakabe Hiyori and the whole world from the Worms that came from a meteorite seven years ago. In the way of saving the world, Tendo meets Kagami Arata. Soon they find a good friend in each other, and when Kagami becomes Kamen Rider Gattack, both start to work together to protect Hiyori and the whole of humanity.