In Korean folklore, an Imugi is an imaginary creature that spends a millennium in water and is able to transform into a dragon upon acquiring a yeouiju (magical jewel). Yook Sungjae stars as Yoon ...

and an Imugi (imaginary creature that is able to transform into a dragon upon acquiring a magical jewel). Kim Young Kwang makes a special appearance as the original form of the serpent Gang Cheol ...