At eighteen years old, Nanase Makoto finds herself being turned out of her uncle’s home. Alone and with nowhere to turn, she makes a startling plea to a stranger: a proposal of marriage. The object of her desperate request is the quiet novelist Hanabusa Chihiro. Instead of dismissing her, Chihiro offers a logical counter-proposal: a contract marriage. He explains that he needs someone to help him protect a large, traditional house in Kamakura that he inherited from a deceased friend. The house, however, has a unique condition. It is an ayakashi mansion, a gathering place for spirits and supernatural creatures.

Chihiro can see ayakashi, but for unknown reasons, he is disliked by them. Makoto, in contrast, is a kind-hearted young woman who unknowingly attracts and is beloved by ayakashi. This unusual compatibility makes her the perfect partner for the role. Their new life together begins in the ancient capital of Kamakura, surrounded by seasonal scenery and a host of eccentric spirits. The story follows the pair as they uphold their agreement to protect the house, gradually developing a genuine emotional bond that complicates their strictly contractual arrangement.

The central characters are driven by their unique circumstances. Makoto is an optimistic and selfless young woman whose life stabilized when she accepted Chihiro’s proposal. Chihiro is a calm and collected novelist who also functions as an exorcist or house guardian. While he is reserved, he strictly honors his promise to protect Makoto. Accompanying him is a mysterious cat that only he can see, which rests on his shoulder. The pair live alongside a cast of invisible housemates, including various ayakashi who are drawn to Makoto’s warmth and find amusement in Chihiro’s stoic demeanor.

The narrative unfolds through several notable arcs. The story begins in the first volume with their initial arrangement, the establishment of their life in the ayakashi mansion, and their early encounters with the supernatural residents. The second major arc introduces a romantic rival. After Makoto purchases a batch of clams, a beautiful ayakoshi named Shinkirou (Mirage) emerges and begins to aggressively court her. This arc, which also includes a date sequence featuring famous locations around Kamakura, tests Chihiro’s stoic patience and pushes the couple to confront their growing feelings for one another.

Later, the peace of the house is disrupted by an event tied to the estate’s tragic past. Makoto discovers a letter addressed to Chihiro from the property’s previous owner, Endohara. This letter is revealed to be a will, written as a warning instructing Chihiro to deliver a specific letter to his friend if anything ever happened to him. The discovery of this letter, combined with a case involving a deep connection to the supernatural world, threatens to shake the fragile but growing bond between the contract husband and wife.