"In/Spectre" is a supernatural mystery anime that blends elements of folklore, romance, and detective work. 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, making her a crucial figure in resolving supernatural conflicts. Kotoko encounters Kuro Sakuragawa, a seemingly ordinary man with a mysterious past. Kuro possesses an unusual ability: he is immortal due to having consumed the flesh of a yokai known as a mermaid. This ability draws Kotoko to him, and she enlists his help in solving supernatural cases.

The series primarily revolves around Kotoko and Kuro working together to address various supernatural incidents, often involving yokai and urban legends. One of the central arcs involves the "Steel Lady Nanase," a viral urban legend about a vengeful ghost haunting a city. Kotoko and Kuro investigate the phenomenon, uncovering its origins and attempting to dismantle the legend before it spirals out of control. Their investigation delves into the psychology of belief and how collective human fear can give rise to powerful supernatural entities.

Kotoko is portrayed as intelligent, resourceful, and deeply infatuated with Kuro, often using her charm and wit to persuade him to assist her. Kuro, on the other hand, is more reserved and pragmatic, often reluctant to involve himself in supernatural affairs but ultimately compelled by his sense of duty and Kotoko's persistence. Their dynamic forms the emotional core of the series, balancing the supernatural intrigue with moments of lighthearted interaction.

The anime explores themes of truth, perception, and the interplay between humans and the supernatural. It emphasizes the importance of storytelling and how narratives, whether true or fabricated, can shape reality. The series maintains a steady pace, blending episodic cases with an overarching narrative that gradually reveals more about the characters' backgrounds and the world they inhabit. "In/Spectre" offers a unique take on the supernatural genre, combining folklore-inspired elements with modern storytelling techniques to create a compelling and thought-provoking narrative.