Ren returns to the town of his childhood, Kaminohara. Strangely, Ren is unable to recall any memories of the town. Meanwhile, his smartphone installs a mysterious game called Monster Strike — heralding the start of a desperate battle!
Ren is forced into a heated battle with the bestial Fenrir X. Unable to control his companion Oragon and on the verge of defeat, a girl appears before Ren. Who could she be?
