Butterflies, Flowers Vol. 1 (manga)

Choko Kuze is the sensible daughter of a venerable family who went bankrupt. She joins a real estate company as an entry-level office worker, but her eccentric boss is harder on her than anyone else in the company! After hearing him inadvertently call her "milady," she realizes he was the young servant boy she knew as a child. At work he's a tyrant, but after hours he insists on treating her like a lady of the nobility. Is romance even possible for a couple locked in such a crazy role reversal?