Metorimetorareai aisu ~Kamen Fuufu wa Soitogeru!?

The story takes place during a transitional period in Japan from the Meiji era to the Taisho era. Sae Ichijōin, a member of an aristocratic family on the verge of poverty, volunteers to take her sister's place in a political marriage. Her partner sees through her façade as an elegant lady immediately, however. A masked man claiming to be the heir to a marquis family comes to her rescue and offers a sudden proposal.