Do you still remember the summer when you were 17? Cicadas chirping, iced watermelon, and a single song looping in the headphones, you stayed by my side, making me mistakenly think that it would last forever. The enthusiastic and lively "young warrior" Gao Xiaonan (played by Lin Yingtong) and the guitar-loving Lei Yuguang (played by Huang Hongxuan) are childhood sweethearts. In order to win the favor of the gentle school grass Wang Zijie (played by Tu Shancun), the tone-deaf Gao Xiaonan bravely signed up for the selection of the heroine of the high school musical, and could only ask her male bestie to help her change her appearance. For this reason, Lei Yuguang launched a fun and funny music training for Gao Xiaonan, vowing to make her the kind of lady that the school grass likes. There were constant embarrassing things in the process of pursuing love, but Gao Xiaonan gradually discovered that her heart seemed to belong to someone else... The secret love and throbbing in midsummer are sweet and bitter. What should she do to make her youth regretless and her first love without regrets?