Anh giữ khóa... Em giữ chìa... Vật đính ước là đây... Vật nhận dạng là nó... Và khi gặp lại... Chúng ta sẽ kết hôn...

Kouta Kazuraba works hard as a part-timer and he thinks that he would like to be a different person in the future. One day, he happened to pick up a Sengoku Driver, the tool for transforming into an Armored Rider, in the forest and started fighting as Armored Rider Gaim to save the people from the monsters named Inves, who came from a different world.