Note: I do not speak Korean, and I’m going entirely by the dubbing and subtitles. There are likely many cultural and linguistic nuances I am missing. E.g. “Master” is frequently used, but not “Mistress”.
Jung Jihoo transfers to the public relations department of a corporation, where he meets a woman with a nearly identical name, Jung Jiwoo. She’s highly intelligent and competent, but ignored or belittled by the department’s sexist boss. Jihoo is actually her superior in the hierarchy, but he tries to listen to her and compromise.
Jiwoo is attracted to Jihoo, but is reluctant to act on it. Her mother and friend both urge her to act on it, but in a stereotypically “feminine” way, which is at odds with her direct personality.
Because their names are so similar, Jiwoo accidentally picks up a personal package delivered for Jihoo, and finds a studded leather collar and leash with the nameplate “Miho”. Jihoo tries to cover for this, but she figures it out, and says nothing.