True Demon Sword, is the sword skill left by Sword Demon, legendary swordsman from 500 years ago. It is a sword skill that is told to be two top most powerful sword skills along with the Sword Art of the Sky Demon. But Sword Demon did not have any apprentice before he died, so it was known to be lost. But in truth, there were three people who Sword Demon taught his skill.
Kingchun, Mu Jurang, and Yin Hongsu.
Three of these geniuses were trained to appoint them as loyal servants and supporters to Chun Muhwa, but the result was a failure. Kingchun and Mu Jurang used their identity of being apprentices of the Sword Demon to force a marriage with the Lord Chun Muhwa. Sword Demon was then disappointed and banished them from apprenticeship. Sword Demon thought that his title of World's strongest man, had tainted his apprentice for greed and never taught the true martial art until he died. And with that, it was known that Sword Demon's one-man clan, Sword Family was said to be finished.