One day, a high school girl named Tsumugi loses consciousness due to an earthquake and wakes up to find herself collapsed in Ginza during the 10th year of the Taisho era. With nowhere to go and in a dire situation, she is rescued by the duke's daughter, Yuitsuki, and begins to live a school life with her. What will become of the future of a girl who has drifted to a distant era…?