Life for the students at Myungsung High School gets a shake-up when Big Daddy, a wildly popular and charismatic idol and influencer, transfers to the school. Things get even more complicated when he appears to fall head over heels for the class president Ha Eun – the most outspoken and popular female student in the class.

But "Big Daddy" is not the only one at the school with a soft spot for Ha Eun.  Yoo Dong Hoo, a sophomore at the school, also has strong feelings for her. But while he is reluctant to make his feelings known to her in real life, online he has become something of an anonymous soulmate for her. He follows her on social media and cheers her from afar by sending her carefully curated musical playlists – full of songs that unfailingly fill her with joy and happiness. Meanwhile, Cha Won Young, another sophomore (and a neat, but often clumsy student) is struggling to reconcile with his best friend after a falling-out.