Ren Homura, a junior-high school student and the lead character of the show, moves back to his hometown of Kaminohara. Though Ren lived there until 4th grade, he somehow has no memory of it.
One day, Ren notices that an app called “Monster Strike” was installed on his phone. When he starts it up, a tiny dragon named Oragon appears. This brings Ren and his classmates, Aoi Mizusawa, Minami Wakaba, and Akira Kagetsuki, together to battle against ferocious creatures and their brainwashed masters.