In a world of mirrored souls, only one person is mirroring another. Those soulmates are linked by sharing pain and minor injuries.

Hajoon had never met his soulmate, and now that he works as a surgeon he doesn't think he ever will, given his long hours in the ER.

One day he feels a massive amount of pain from his soulmate and suddenly, a patient comes in just an hour later with the same injuries. He doesn't brush it off as a coincidence. Ha-joon knows this is his soulmate.