The protagonist Takigawa Nanase is a super normal modern day female high school student.
The story starts to move when she discovers an old diary in a storehouse on the grounds of her house. When she opens the diary a strange light jumps out and she gets sucked into the book.
When she came to her senses she had arrived at a street that was completely unfamiliar and different from her modern time.
Somehow she had time traveled to the Taishou Era!?
Not understanding the situation Nanase was unable to move, It was looking likely that she would be found and attacked by some suspicious men.
But suddenly she was saved by a gentle hearted youth Takami Touma and his attendant Fujima Kounosuke.
By Touma's kindness, Nanase was taken under the protection of the Takami household and went to live in their mansion.
But what was waiting for her there was a rather cruel fate.
"If I can change the past, I can save you? Or..."
A single girl, In an era that isn't her own, will become a strong noble woman...
(Translated from the official site)