The transfer student Yebom was jealous of Eunho, an honor student everyone liked. Many years later, Yebom's life feels hopeless and bleak when one day, she finally learns about the reason behind Eunho's death that occurred a long time ago. Yebom, filled with regret, returns to the time when she was 18 and faces him once again. What drove the seemingly perfect boy to death? Yebom is finally ready to hear Eunho's story.