Ryu is a talented young writer who has a girlfriend, Pin, whom they have been dating since high school.They love each other and plan to get married.But maybe because of Ryu's fate, he lost her forever in a car accident.

Ryu blamed himself, became decadent and started drinking heavily.With the arrival of Arm, the grandson of the boss of the company where Ryu works, and the relationship they gradually build, Ryu's world begins to become bright again.When Ryu discovers that he has cancer and may not have long to live, Arm devotes himself to caring for him and the two decide to live together.

However, the world is always cruel.When Arm and Ryu learn the truth about the events that led to their breakup, Ryu disappears from Arm's life.Arm tried every means to find Ryu, but never succeeded. Until finally, Arm got a box that contained all the answers.