Kyungsoo and Chanyeol are happily married with children. One day, Kyungsoo wakes up and finds himself 14 years in the past where he is still single and the children have not been born. Now, Kyungsoo has to make Chanyeol fall in love with him all over again. The catch is, they were enemies in the past and Chanyeol still despises Kyungsoo for a past tragedy.

Prince Kyungsoo of Vallis was never set to inherit the throne because he was born an omega. Thus, being sent off to marry Crown Prince Chanyeol of Zerura was an even bigger blow to him. However, Chanyeol doesn't want this marriage as much as Kyungsoo does and they conspire to give each other what they want, only to end up unraveling more secrets and having to face unresolved feelings.

Chanyeol, a sorcerer, decides to use forbidden magic to survive in a world where magic is dying. Through dubious means, he “marries” Kyungsoo, another sorcerer. Chanyeol is just using Kyungsoo as his personal blood bank; but his plan backfires when he begins to fall in love with Kyungsoo and contracts the Hanahaki disease as a result of his unrequited love and unexpected feelings.