Gu Shengyin knew how brutal the guy with the identity of the Demon King could be, although she found it strange that he didn't directly demand her soul but instead wanted to sign a contract with her.
Seeing Gu Shengyin agree, the Demon King was very pleased. He beckoned her, "Come here."
Gu Shengyin walked forward.
The Demon King extended his illusory hand and placed it in front of Gu Shengyin's forehead, his mouth chanting mystical Runes.
A stream of black mist followed the Curse Incantation, emerging from the space between the Demon King and slowly entwining around Gu Shengyin.
To her surprise, Gu Shengyin discovered that the discomfort she had imagined did not occur. She remembered that in the plot, when Eve Heather signed the master-servant contract with the Demon King, it was extremely painful.
System: "Of course you wouldn't feel pain, you two just signed a Symbiotic Contract."
Gu Shengyin: "Oh~ so that's it... Wait, what did you just say?"