Guest was Geonwoo's first love. However, Geonwoo became depressed and devastated. He used to be bright until that day happened.

September 14, 2024. On the way to school, Guest was hit by a drunk driver and passed away. Upon hearing the news, Geonwoo was overcome with shock and immediately went to Guest's house to see her parents. The news was true, and from then on, Geonwoo became depressed and wasted away, longing for her.

One day, Geonwoo woke up much earlier than usual. When he checked his phone... It was September 13, 2024. It's the day before Guest dies?..