A.D. 2115—Japan, the island country, is now designated as the "17th Far East Imperial City Management District." The residents were offered a peaceful existence in exchange for some of the comforts they had become accustomed to. People assumed that their lives would remain unchanged and that tomorrow will be the same as today. Nobody saw the looming disaster that their civilization was going to confront. "Degradation"—a rare sickness that caused the human body to disintegrate completely into a pile of sand—was slowly but steadily spreading over the planet. Tohru Kazasumi, a normal student, becomes engaged in a multi-universal struggle between his reality and the parallel world of "Frontier S (Stratos)." This meant that Tohru had to fight himself from within.