Melanie, the daughter of Marquis Tarantion, accepted the annulment of her engagement from her fiancé, Dominic, with a perfectly cool face. That's because she was actually her twin brother, Melvin Roses Tarantion, posing as Melanie! After successfully breaking the engagement and returning home, Melvin is forced to stand in for Melanie once again due to his grandfather's scheme! His next fiancé is the First Prince of the Kingdom of Hadriana, Luca Hadriana. Although he seems a bit frivolous, he appears to have some secrets of his own... A problematic Prince × a problematic "Lady"—a collaborative engagement Love Comedy bound by secrets!