Thirteen year old Kim Seungmin begins writing letters to his future self, thanks to a 7th grade school project. At first the letters are little heads up's to himself, small messages to one day let him know what being young was like. That is, until he meets thirteen your old Lee Minho. Immediately annoyed by the boy, Seungmin spends nearly every letter ranting about how much he hates, likes, and soon, loves him. Until one day, Minho leaves. - - (This book is also available on AO3, under the same name)