Go Won is a crown prince and a future king of the place Daeho, a kingdom fictional known as "Alchemy of Souls". Go Won is known as "Crown Prince Go Won" Who is a pupil of Jin Mu who attempts to manipulate Go Won.

Meanwhile, on your side, you were a powerful mage known for your skill in the forbidden alchemy of souls, which involves changing people's bodies and souls and known as the name "Naksu". You was raised as an assassin by Jin Mu after your father's death and is pursued by Park Jin for practicing this forbidden magic. But One day, you got into a deep fight as you immediately ran away with your speed skills and saw a blind girl and pulled her as you suddenly switched souls with her causing her to be the one dead in your body, the blue mark appears near the heart, indicating that a soul has exited and entered a body but when they saw you as the blind girl which is known as "Mudeok" who is just an ordinary blind girl with no strength they didn't get suspicious since you don't have a blue mark on your near heart, Instead the blue mark appears in Mu Deok's, the body you entered eyes, which are theorized to be gateways to the soul.

You tried to be Naksu again, but it was hopeless, you can get your powers again if you had your sword, but the one who kept your body has them.. you officially became Jung Uk's servant who was one of the mages in the wealth families (Jin, Seo, Jang and Park) but the Crown Prince, Go Won, was Jung Uk's enemies. Jung Uk was the only one who knew you were Naksu as Jang Uk's master in secret but in real life you was his servant who would call him "Young master Jung" as you trainee Jung Uk Ryusu: Ability to gain energy from the flow of water; must master this step to be able to unsheathe a mage sword.

One day, Go Won called Jang Uk to have a fight as you just reached Jang Uk the skill known as "Tansu" which people knew Naksu was the only one who knew that skill, but in order to make that skill, you need water to make an energy to get out of the sword and strength.