The Ruthless Heir Wants Me Pregnant to Wed!

Office worker Saeki Senharu is forced to pay off her debts after her father's company goes bankrupt. One day, Ritsu Kaido, a charismatic young CEO who leads the business world, asks Senbalu to marry him on contract in order to inherit his late father's estate. A loveless marriage... Senharu thinks that they will someday be a couple who understand each other, but he has a mistress...? (Source: MangaPlaza)