In a world overrun by mysterious beings known as Objects, humanity survives by studying, containing, and—when possible—destroying them.

After dying, an ordinary researcher awakens as the Gray Reaper, a small humanoid Object with overwhelming power and an instinctive curiosity about the strange world around her.

Taken in by the Se-hee Research Institute, she spends her days wandering into anomalous incidents, befriending bizarre Objects, and uncovering mysteries that gradually grow far beyond Seoul—and even Earth itself.