Gakeppuchi Reijou wa Kurokishi-sama o Horesasetai! summary:
My family is in debt, and we don't have enough money for my sick sister's treatment... The troubled noble, Clarice, finds herself engaged in a political marriage with the most feared Black-Knight in the kingdom, Frost, known for "slaughtering beasts with his bare hands". In an attempt to secure the fortune, Clarice tries to seduce the "Black-Knight", but just as she does, she discovers "her" secret...