Sehun is a doctor living a regular, modest life in Seoul, Korea. With a normal apartment by himself. That is until one faithful night, after a particularly long shift, while Sehun is driving home. Tired and falling asleep at the wheel, the doctor manages to avoid a head-on collision but swerves off the road and into the ocean. After a blinding white light, Sehun finds himself in a strange world full of fantasy and without technology. Desperate to get home, he enlists the help of several people. Including Kai, a stubborn, hot-headed warrior; whom Sehun finds himself falling for. It makes the doctor think that perhaps, for the right reasons, he could stay.