When Kyun-Woo runs into a drunk girl on the subway, he ends up helping to deal with her situation as everyone on the train mistakenly believes he is her boyfriend. After a major ordeal in the process, he eventually comes to meet the girl under more normal circumstances. She is outspoken, very dominating - almost abusive. But, nonetheless, they start to develop a "unique" relationship. "My Sassy Girl " is based on the real life internet-posted chronicles of Kim Ho-Sik about his relationship with his girlfriend.

A devil-may-care police woman, Kyung-jin, gets to know a kind-hearted high school teacher Myung-woo when she mistakes him for a thief. After an awkward first encounter and a few more coincidences they start to become fond of each other. Although Kyung-jin is one tough girl, Myung-woo is always worried about her because of her recklessness. One day, when Myung-woo tries to help Kyung-jin during her risky pursuit of a criminal, an accident happens which causes Myung-woo's death.  After the accident, Kyung-jin feels empty and lonely so she throws herself into perilous situations.  However, whenever she falls in danger she feels that a strange but familiar sense in the wind is helping her out.