In the midst of his ordinary high school life, Akira Nikaido's world transforms when he encounters the enigmatic Shirogane, who reveals a shared destiny with him. Initially skeptical, Akira's disbelief shatters when a shadow monster threatens him during a late-night search with his friend Aya. Shirogane unveils the disruption in the equilibrium between the human and shadow realms, urging Akira to embrace his fate as a 'shin' to mend the fragile balance. While the anime delves into shonen-ai undertones, such elements are notably absent in the manga adaptation.