Head of the R&D department of a biotech company, people refer to 30-year-old Ai Li Si as a robotic and cold woman. At the age of 17, she is a positive and optimistic girl. Her warmth makes her good at caring for other people, especially her friends. She is best friends with Bai Shu Lei and Liu Xiao Fen, and eventually He Hao Yi. One day, an incident happens that causes Ai read moreLi Si to be misunderstood by her friends and other classmates. Her friends begin to ignore her and her classmates begin to give her a hard time. Because of the aftermath of the misunderstanding, Ai Li Si decides to leave. Now, 13 years later, He Hao Yi comes back from America to work at the biotech company and is reunited with Ai Li Si. He tries to work out what happened to her, but she gets into a small accident causing her to forget the past 13 years soon after. He Hao Yi continues to work towards finding out the truth about what happened when they were 17 to cause Ai Li Si to become so cold and robotic.