On the night of a crimson full moon, Ayazuki Mei, a female high school student, is enticed to enter a magical box by a mysterious magician named Charlie. When she awakens, she finds herself in an unfamiliar park.

During the party at the Rokumeikan, Mei is treated like a suspect by a police officer named Fujita Goro, but Ougai pulls her close and calls Mei his precious fiancée.

Now that it is clear that Mei is a Tamayori who can see ghosts, she decides to help Syunso find the black cat that became a divine spirit. While conducting their search, they get drawn into an investigation of paranormal happenings at a hotel.

Ougai admits to his aunt that Mei is his fiancée and that he intends to formally present her as such at a party being held at the Rokumeikan the following month. Sensing Mei distress at this, Ougai invites her out on a date to Asakusa.

Mei undergoes strict instruction from a geisha named Otoyakko to become a proper lady worthy of being Ougai's fiancée. She struggles desperately to learn how to wear a kimono, how to carry herself, and etiquette.

Mei demands to help Otoyakko with a big party, but is Mei ready to serve Japan's elite?