During their high school days, there was mutual disdain between Han-Eol and Da-Hae as she was thought of as a bully and he as a jerk. However, fate brings them together years later at their siblings' wedding. Tragically, the newly married couple passes away, leaving their loved ones to contemplate if there was anything they could have done to prevent it. In an unexpected turn of events, Han-Eol and Da-Hae find themselves back in high school with their siblings alive. With just a diary and each other for assistance, they set out to alter their siblings' fate. But, will they be successful in doing so, or will destiny repeat itself?
