The story takes place in the Meiji and Taisho eras, a time of dramatic transformation in a certain "Great Japanese Empire." Ichijoin Sae, a member of a struggling aristocratic family on the brink of collapse, volunteers for a political marriage in her sister's place. However, her makeshift "lady" persona crumbles, and she is instantly humiliated. Just then, a masked man appears. He, too, has his own agenda. The masked man, whose face is hidden from Sae, suddenly proposes marriage. What are his true intentions?!

The zero-day marriage between the masked man, whose true face is hidden, and Sae, raised as the "heir" of a marquis family, begins...

(Source: Kadokawa, translated)