Kang Hyun Ho has never had a boyfriend in her life. She begins swimming lessons at a sports center. There, she develops a crush on Jo Woo Jin. Meanwhile, Han Yoo Ra is Kang Hyun Ho's swimming instructor. He develops feelings for her

Miss Kim is a mysterious contract worker at a company. She keeps a low profile at work, but she is smart and has an excellent memory. Mr. Lee is an enthusiastic rookie employee at the company. He always seems to be near Miss Kim.