It was the Joseon Dynasty, on a very quiet and eerie night when a uniquely blue moon hung in the sky.

King Doheon could not sleep, despite the quiet atmosphere of his bedchamber.

Doheon, who had been reading a book, decided he couldn't stay like this and went out for a night walk.

At the same time, hiding in the cold riverbed, an Imugi that had waited a thousand years for this day to become a dragon revealed itself as a massive white snake and flew toward the sky.