Sehun meets a boy his age on the first day of summer, except he is a little bit different: he has progeria and as a consequence isn't able to do everything other children his age can. Their friendship blossoms, teaching Sehun about what it means to be a true friend in the process.

Please note that this is simply an adaptation of progeria syndrome, but not all of the symptoms will be included, such as baldness, because Luhan's hair is really too pretty to do away with.