Kon’yaku haki desuka? Hai yorokon de. Datte boku wa ane no kawari desukara!

Melanie Tarantion, a marquis's daughter, calmly accepts her fiancé Dominic's abrupt breakup—because she's actually her twin brother Melvin in disguise. After escaping back home, Melvin is forced to play sister again thanks to his grandfather's schemes, this time betrothed to Prince Luca Hadriana. A secretive playboy prince and a hidden-identity "lady" team up for a collaborative engagement comedy.