Ryuushi no Hanayome - Shinryoku no Otome wa Seiryuu no Shugosha ni Aisareru

"I am Grantley Singulair. I am the man who will be your husband."
After the death of her mother, Alicia, a viscountess, lives as a servant under her father who is indifferent to her, while her stepmother and stepsisters abuse her.
One day, while enduring the memories of her childhood at the flying dragon office, she receives an engagement proposal from her sister-in-law.
The man is Count Singulair, who has a large scar that can be seen even under his eye patch, and is said to be a terrifying man with icy eyes.
But on the day of their meeting, it is the young master of the Flying Dragon Flight who shows up...!
Alicia is to marry him instead of her sister-in-law...?
A Cinderella story that begins with a substitute marriage!