The protagonist lives with her mother in a tenement house in the Shinbashi section of the Imperial capital. Having lost her father in an accident, she works to make a living to support her sickly mother.

At the shrine she visits every day, the 16-year-old protagonist hears an unfamiliar term.

"I wish we can ask help from the Ryuuseigumi…"

Her daily life continues. She continues to live in poverty, just barely able to afford her mother's medicine. She imagined how the life of the women in western clothes that often passed by on rickshaws are like.

(Evening balls, where women in western clothes and men dance together… sure sounds nice…)

Then one day after she returned home from work, she received a set of clothes from an unknown sender. It came with a letter with just one line: "Wear this and attend the next Sairyoku House’s evening ball."

After some hesitation, the protagonist decided to wear clothes and attend the evening ball. Her lack of dance experience, the unfamiliar clothing, and the overwhelming building made her very nervous—.

"…Don’t you want to know the truth about your father’s death?"

A mysterious man said to her from behind, but when she turned around, no one was there.

After returning to the tenement house, she asked her mother about her father's death, only to discover a surprising truth. To uncover the mystery of her father's death and fulfill his wish, the protagonist and her allies rise to action—!