In 2023, Eun Gyeol (Ryeoun) is a high school student with a passion for music—a model student by day and a wild guitarist in a band by night. When he stumbles upon a strange and intriguing music store, he finds himself instantly transported back in time to 1995, face to face with his father, Ha Yi Chan (Choi Hyun Wook)—who is also a high school student! It turns out that Yi Chan thinks Eun Gyeol is crazy when the young man calls him “Dad”—and, even worse, it seems he has a crush on an icy cellist named Se Kyeong (Seol In Ah), who isn’t Cheong Ah (Shin Eun Soo), the boy’s future mother! In a long shot attempt to "set things right," Eun Gyeol joins a band led by his father… but will this be enough to bring his future parents together, and will he ever manage to return to the 2020s?