Warrior of the New Century

The hero is dead, and the next one is Raino.

In order to survive, the only way Lei Ye could think of was to swallow the 'gender change potion. The demon' transformed into a beautiful girl.

but...

But the Demon King laughed and said, "Do you think I would just stand there and buff like an idiot?" He ran over, snatched the potion, and drank it all in one breath?