In a retro-futuristic world cloaked in shadows and cosmic bureaucracy, Anna—an immortal "Observer" known as the “Error Lady”—exists outside the system itself. When Loid, a boy she once saved and now a powerful entity called the “Devouring Satan,” reunites with her aboard a spectral train, long-buried questions resurface. Bound by roles as Higher Spatial Life Forms (HSLF), the two form a fragile pact to face corrupted spirits, forgotten histories, and a world where identity is data and memory holds weight.
But as glitching truths emerge, they begin a haunting journey through a reality that records everything—except forgiveness.