"In/Spectre" is a supernatural mystery anime that intertwines folklore, detective work, and romance. The narrative centers on Kotoko Iwanaga, a young woman who becomes the Goddess of Wisdom for the supernatural world after losing an eye and a leg to yokai, or spirits, as a child. Her role grants her the ability to communicate with and mediate between humans and yokai. Kotoko encounters Kuro Sakuragawa, a man with a mysterious past involving immortality, after he breaks up with his yokai girlfriend. Recognizing his unique abilities and potential, Kotoko enlists Kuro to help her solve supernatural cases and maintain balance between the human and spirit worlds.

The series primarily revolves around their partnership as they tackle various supernatural incidents, often involving yokai and urban legends. One of the central arcs focuses on the Steel Lady Nanase, a viral urban legend about a vengeful spirit haunting a city. Kotoko and Kuro investigate the phenomenon, uncovering its origins and the human motivations behind its creation. The story delves into the interplay between human belief and the supernatural, exploring how myths and legends gain power through collective fear and imagination.

Kotoko is portrayed as intelligent, resourceful, and deeply committed to her role, though her infatuation with Kuro adds a layer of personal motivation to her actions. Kuro, on the other hand, is reserved and pragmatic, often serving as a grounding force to Kotoko's more impulsive tendencies. Their dynamic evolves as they work together, blending elements of mystery-solving with subtle romantic undertones.

The anime balances episodic cases with an overarching narrative, gradually revealing the complexities of the supernatural world and the characters' backstories. Themes of trust, deception, and the consequences of human actions are woven into the plot, creating a layered and engaging story. The series maintains a steady pace, blending suspense, humor, and emotional moments to create a cohesive and compelling viewing experience.