I'm a Demonic Cultivator, So Why Am I Going Undercover in an Immortal Sect?

He had just transmigrated into the body of a demonic sect disciple when an alliance of immortals and demons attacked the mountain. The demonic path was on the brink of annihilation! Si Yan looked at his master in confusion. “What do you mean, I have to join an immortal sect as a spy?” His master replied, “My good apprentice, it’s the only way to preserve the legacy of our demonic sect!” Si Yan watched helplessly as a powerful figure from an immortal sect killed his master with a flick of his finger, his heart heavy with grief. To preserve the demonic sect’s legacy, he used a mysterious gray stone to replace his extraordinary innate constitution, becoming a disciple of the immortal sect. He cultivated both the immortal and demonic paths, cautiously hiding his identity as a spy. Yet the more he cultivated, the stranger everything seemed. Why was there always some invisible hand covering for him whenever he was about to expose himself as a spy for the demonic path?! Then one day, the powerful figure from the immortal sect who had killed his master called him “Junior Brother,” and Si Yan was completely dumbfounded…