After his mother's sudden and inexplicable death during his childhood, Shin Hazama distances himself from the world. His father becomes consumed by research, leaving Shin with only one dependable ally: Kotori Izumi, his childhood friend and the daughter of his father's boss. Kotori, who is both popular and compassionate, helps Shin make it through the years. Shin and Kotori grow rapidly, both personally and in their relationship, reaching the end of their third year of high school. However, their progress comes to a sudden halt when Shin's father dies unexpectedly. Before they can process this tragedy, they uncover a shocking truth about the circumstances surrounding Shin's parents' deaths. They encounter agents from an alternate universe's advanced and dystopian Japan, including Jin, Shin's "alternate self." Jin battles Miko and Niko, two humanoid weapons, with two objectives: to keep Shin out of harm's way and to eliminate Kotori. This is because Kotori's corresponding self, Princess Kotoko, is Jin's arch-nemesis and responsible for his parents' deaths. In the aftermath of this stunning revelation, Shin and Kotori must confront their true feelings for one another despite the looming end of their reality. Because the destinies of their corresponding selves are intimately intertwined, Shin and Kotori must navigate this hazardous and intricate situation.