In The Night, At The Duke’S Mansion summary:

Read manhwa In The Night, At The Duke's MansionAristasia, a noble lady of the Verdick family, who's loved by the cold blooded duke and the sword master. Long after her debutante, she didn't have a significant lover. She was curious about s** and her body became heated, and while she avoided her brother's eyes, she waited for a gigolo and her brother Evan came. I see, Aris. You were curious about what you would do with a gigolo, but I don't like that a gigolo will come. So wouldn't it do if I, your brother, just told you?' After that night, her brother's view of Aristasia changed.