Ga Ram and Seon Jae live together as they prepare for marriage, but their relationship is a bit rocky these days. A misunderstanding leads to an argument, and Ga Ram suggests that they take some time apart. However, when Ga Ram gets into a car accident, Seon Jae jumps in to save her. Ga Ram wakes up in a strange place where she must bargain to save Seon Jae’s life.

Ga Ram returns to a week before the day she died and becomes frantic about having to break up with Seon Jae. When Seon Jae suggests that she must have had a bad dream, Ga Ram believes him and tries to go back to living her life. However, when she and Seon Jae make up after an argument, something goes wrong.

Seon Jae recovers from his sudden loss of consciousness in the emergency room. Meanwhile, the man from the afterlife returns and tells Ga Ram that her death was not a dream. She must break up with Seon Jae if she wants to save his life. The next day, Ga Ram’s estranged mother suddenly shows up at the house.

Ga Ram storms out of the house after hearing that Seon Jae lent her mom some money. Seon Jae insists that he go with her to see her mom. Despite seeing that her mom is in a dire situation, Ga Ram’s resentment doesn’t ease up. Seon Jae tries to help the mother and daughter reconcile, and Ga Ram finds it harder to have to break up with him.

Ga Ram breaks up with Seon Jae and leaves him with Hee Jeong at the restaurant. As she packs her things and moves out, the mysterious man shows up in the room, and she tells him to keep his promise. Meanwhile, Hee Jeong tries to convince Seon Jae to get together with her, and Seon Jae tells her the truth that no one knew about.

Seon Jae struggles to accept the fact that Ga Ram broke up with him. While at work, he is told to go meet a client for lunch. The supposed client turns out to be the man from the afterlife. Meanwhile, as Ga Ram tries to get her affairs in order to leave this world, Seon Jae goes to see her.

After being turned away by Ga Ram, Seon Jae runs into a man and is instantly transported to a mysterious place. However, Seon Jae wakes up to find himself in the Emergency Room. Meanwhile, Ga Ram is determined to save Seon Jae by accepting her own death, but Seon Jae finally pieces together why Ga Ram insisted on breaking up.

Ga Ram accepts Seon Jae’s suggestion that they spend one last day before saying goodbye. They revisit places from their memory and Ga Ram prepares herself to bid Seon Jae farewell. The time for Ga Ram to die approaches, but Seon Jae asks her to wait for a gift he got her. When Ga Ram realizes Seon Jae’s intentions, it is already too late.

Seon Jae is rushed to the hospital, but the blood loss and brain damage leaves him in critical condition. Ga Ram is devastated, but she decides to listen to Seon Jae’s wishes from his letter. Three months go by and Ga Ram lives her life to the fullest each day. The man from the afterlife resents how Ga Ram can still be so happy, but her determination finally makes him give up.