Since the mysterious and sudden loss of his mother in childhood, Shin Hazama has closed off his heart. Their bond, forged through shared grief and quiet support, becomes the only anchor in this chaotic world. With a scientist father absorbed in research, he depends only on his childhood companion Kotori Izumi, the well‑liked and amiable daughter of his father's employer. As graduation approaches at the end of their third year of high school, Shin and Kotori finally begin to move forward together, both in life and affection.
Everything crumbles once more when Shin"s father also dies abruptly. Before calm can return, they uncover the truth behind their parents" sudden deaths by meeting agents from a high‑tech dystopian Japan in a parallel universe. Among them is Jin, Shin"s "relative self," who opposes the humanoid weapons Miko and Niko. Because relative selves share a bond, Jin has two aims: protect the vulnerable Shin to safeguard both their lives, and eliminate Kotori to break the iron rule of her relative self, Princess Kotoko—his arch‑enemy and the killer of his parents. Facing this new reality, Shin and Kotori must truly confront their feelings for one another, even if the world they know ends tomorrow.
