Dear Heroes, I really am a Villain - Chapter 11: Blood Mongoose, Full Assimilation

Forget about moving to the other side of the world and starting over.The Apocalypse is here!As the only survivor of the Tutorial Quest in his area, Elijah awakens the Class of “Depraved Hero”, an ominous-sounding Class with a Legendary Rank!Additionally, because of the insane difficulty as well as his Clear Rank, he gains the Skills that, according to the mysterious figure that is the Administrator, he needs most.[You have Developed the Skill “Absolute Authority[A]”.][You have Developed the Skill “Slave Mark[C]”.]

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

Feng Lingxi was the traditional family’s head mistress – a person with a charismatic yet sly personality with the ability to attract people easily to her side, and having the potential to take someone’s soul away. Crossing across boundaries from a decade ago to now, a world that gives woman full respect and acknowledgement….

Don’t be fooled by her, because she was someone who would act obediently in front of a crowd but, stabs them in the back when necessary! Disguising as someone that would gain her trust and belief! That was why the Emperor of Xian started doting on her, allowing her to become absurdly daring to do whatever she liked. This made the Empress speechless to tears.
That would be the cause of the kingdom’s downfall in the near future…

- Description from Novelupdates

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.