During a lunar eclipse, mechanical engineering student Kim Yong connects with fellow student Kim Mu-nee via a vintage HAM radio borrowed from his best friend. Kim Mu-nee needed an interviewee for her term paper, and so the two agreed to meet the next day. Although both arrive on time and at the same location, they somehow manage to miss each other. Confused and frustrated, they soon discover something impossible: they’re living in two different time periods. Kim Yong is living in 1999, and Kim Mu-nee is living in 2022. But despite the insurmountable time difference separating them, both students form a deep bond via their radio communications, exploring their friendships and romances, and helping each other navigate some of life’s hardest decisions.