There's a Demon Lord Who Dotes on Me

Five thousand years later, she awoke as the only immortal exalted in the Three Realms. With nothing better to do, she descended to the mortal world to undergo a tribulation, and a Demon Lord followed right behind her, spoiling her rotten. Together they healed the sick and saved lives, were hunted, and beat up the powerful… It was only when the demon race repeatedly attacked the immortal realm that the immortals realized the only god in the world had fallen to demonic ways…