Tak Dong Kyung is an editor for a web novel company. She has led a tumultuous life, subject to the whims of fate, and she soon finds herself on the precipice of true destruction. Myeol Mang, the existence of a middle manager between God and humans, suddenly appears in her ordinary life. He was born between the dark and the light: when he breathes, countries disappear; where he walks, the seasons collapse; when he smiles, a life is extinguished. All he has to do is exist for something to fall into ruin. This is not his intention, but simply his fate. Dong Kyung makes a 100-day contract with him, risking her life and her love. Myeol Mang eventually forms a relationship with her, who curses the whole world, as she drags him into her life with her fierce desire to live.