Dareka Kono Joukyou wo Setsumei shite Kudasai! Keiyaku kara Hajimaru Wedding

If you thought regular marriages were insane, wait until you see the contract Viola signed! Our heroine, the daughter of an earl, signed herself away in a marriage contract to an aloof duke, Cersis, in order to save her family from a lifetime of poverty. All of a sudden, Viola's life is turned upside down when she moves into the Fisaris family's manor and is left to negotiate her new life as a "show wife" in a world she had only ever caught glimpses of before. How will she shake things up at the Fisaris estate?

(Source: J-Novel Club)