Bae Songwoo has been secretly in love with his close friend, Kim Sangjin, for a long time. He's been living in secrecy, keeping his feelings to himself. One day, while going about his day-to-day life, Bae Songwoo stumbles upon a mysterious book in his home. Upon inspection, he discovers that the book reveals the intimate details of Kim Sangjin's life story.
But Bae Songwoo feels like an insignificant character in the grand scheme of things... Or so he believes. As he tries to dismiss the book's contents, Bae Songwoo soon comes to the startling realization that his life is beginning to follow the story's plotline to a T.
