In high school, he thought she was a bully and she thought he was a huge jerk. Years later, Haneul and Dahae meet again... because their siblings are getting married! But tragedy strikes the newlyweds and their loved ones are left to wonder how they could have saved them. Haneul and Dahae awake to find themselves in high school again—and their siblings are alive! With only each other and a diary to rely on, can they weave a new destiny for their siblings? Or will fate unravel all the same?