The Dying Villainess's Path to a Happy Ending

As Clea Rino died, she made a desperate plea to make her wish come true. The demon king, fascinated by this, hastily injected the soul of someone from Korea into Clea's body and proposed a deal. If Clea's wish comes true, he will let the wayward soul go back to Korea. Now, the new inhabitant of Clea's body has to successfully remain happily married to Grand Duke Isaac Detroi for six months, deal with everybody in the nation hating her, and survive in Clea's frail body, which is actively trying to kill her (again) with every step she takes.