Busan, 1998. A high school girl, Pak Se-ri, although she swore she would never invite guys on a date first again, decides to break her rule for the school’s heartthrob, whom almost every girl is in love with. To take such a serious step, she needs to prepare properly, namely to straighten her unruly curly hair. The only salon that can do this with a guarantee is run by Pak Yun-seok’s mother, the girl’s new classmate, who recently broke his leg and nearly drowned. Se-ri begins helping Yun-seok in exchange for a free hair-straightening procedure.