Standing at the pinnacle of the leading conglomerate TK Group is the perfect man, Tae Junseop. He is more appealing than fictional male leads, and his beautiful relationship with his non-famous girlfriend often makes headlines. In comparison, his cousin Iseop feels inferior; even after a decade of dedication to TK Group, he has lost out to Junseop in every way, and to top it off, he has no dating experience whatsoever.

The efficient Kang Mingyeong has been TK Group's star employee for 10 years. She entered the workforce at the same time as Iseop, and she has been climbing the corporate ladder with ease, making her yet another target of Iseop's envy. When Junseop suddenly assigns her as Iseop's personal assistant, she faces real challenges: Iseop behaves childishly, hates when others touch his belongings, and appears to absolutely despise work. For the sake of her family, Mingyeong perseveres through the hardships of serving such an unpredictable man, and gradually his quirks seem more like a thin veil hiding his unexpectedly adorable personality.