In the futuristic A.D. 2115, what was once Japan is now the '17th Far East Imperial City Management District,' where peace was promised in exchange for some comforts. Amidst the belief that life would remain unchanged, a deadly disease called 'Degradation' emerges, turning humans into sand. Tohru Kazasumi, a regular student, gets entangled in a cosmic clash between his reality and the parallel world of 'Frontier S (Stratos),' pitting him against his doppelganger. Their destinies intertwine as they confront each other. Can these worlds ever reconcile and find harmony?