It's full of 4 years bright, beautiful and painful story of teen and young adult in their youth.
I root for Hee Do really much, her character really bring what grit means to never give up on something you passion and love to do
Its also the time when the beautiful friendship form between these taeyang highschool kids and Yijin, a young adult who get a strength to rebound from Hee Do
Its really beautiful friendship and love story that's really reflect the style during the era .. its not showing passionate kinda love but more to kinda love that thrills you even with the simple act
No matter how beautiful a moment, it won't last forever

Its one of the best story out there with solid acting