Gossip & Gunmetal

Melody, a genius researcher, transmigrated into Nocturne’s fiancée. She vowed to play the bystander, make money, and step aside once the "Ninth Madame" came. On their wedding, Nocturne heard her inner voice, "Is this the Nocturne who fools around with the Ninth Madame?" He was confused that father only has eight concubines. Where did a ninth come from?