"Taishō Mebiusline Chicchai-san" is set in the Taishō era of Japan, a period marked by cultural transition and modernization. The story revolves around a young man named Chicchai-san, who works as a clerk in a small government office. His life takes an unexpected turn when he encounters a mysterious woman named Mebius, who possesses supernatural abilities tied to the spiritual and occult phenomena of the era. Mebius is revealed to be a "Mebiusline," a being capable of manipulating time and space, and her presence disrupts the ordinary flow of Chicchai-san's life.

As the narrative progresses, Chicchai-san becomes entangled in a series of supernatural events and conspiracies involving other Mebiuslines, each with their own motives and powers. These beings are connected to a larger, enigmatic organization that seeks to exploit their abilities for unknown purposes. Chicchai-san, despite his initial reluctance, is drawn deeper into this hidden world, where he must navigate the complexities of loyalty, morality, and the consequences of meddling with forces beyond human understanding.

The series explores themes of fate, the clash between tradition and modernity, and the ethical dilemmas posed by supernatural powers. Chicchai-san's character evolves from a passive observer to an active participant, as he grapples with his role in the unfolding events. Mebius, on the other hand, serves as both a guide and a catalyst, her enigmatic nature adding layers of intrigue to the story. Supporting characters, including other Mebiuslines and government officials, contribute to the tension and mystery, each playing a part in the larger narrative.

The plot is driven by a combination of episodic supernatural encounters and an overarching mystery surrounding the true nature of the Mebiuslines and their connection to the Taishō era's societal changes. The series balances moments of suspense, action, and introspection, creating a narrative that is both engaging and thought-provoking. Through its exploration of historical and fantastical elements, "Taishō Mebiusline Chicchai-san" offers a unique blend of period drama and supernatural intrigue.