What's Wrong with Secretary Kim

The series revolves around the narcissistic Lee Young Joon, the vice president of a company run by his family. He is very self-absorbed and thinks highly of himself, so much that he barely acknowledges the people around him. Lee Young Joon has a capable and patient secretary Kim Mi So who has remained by his side and worked diligently for 9 years without any romantic involvement. However, Mi So now wants to set her life & focus on herself so when she decides to resign from her job, hilarious misunderstandings ensue. After 9 years of their strictly-workplace relationship, can it now develop in something more?
(Source: AJ at MDL)
~~ Adapted from the webtoon "Kimbiseoga Wae Geureolgga" (김 비서가 왜 그럴까) by Jung Kyung Yoon (정경윤).