Five years later and the exchanges of letters between Eunji and Naeun didn’t end, nor even slowed down. However, it just gets harder. Naeun will soon move to London, and as the distance between the two pen pals starts to widen, the two decided to meet one last time before the sixteen year old’s flight overseas. Now, riding a train that leads to Seoul, Eunji starts flashing back memories of the letters Naeun had sent her from day one.