From Heartbreak to High Society - Chapter 15: Uncharted Horizons

The king of assassins was reborn, mastering both alchemy and poison. Sitting inside the space, there was a ghost that loved crying.

Once a regular high school student, the protagonist gets sent to another world via truck. He reawakens to find himself contracted to a girl about the same age as him before passing, and that his body was no longer that of a human. Given a new name as the girl's contracted spirit, he spends his days at her side._ _ _ _ _ _ _ _ _ _ _This is not a novel I will be updating multiple days a week. The most likely outcome is me updating it once a week, but if any readers would like to read my other works, I would like to suggest reading the story I update most which is “Level One Isn't Weak!”.

The formless ancient world was infested with despicable demons. They hunted and feasted on mankind, keeping the human civilization constantly in a weak and suppressed state.

During the first known year, a magical mountain descended into the world from the realm of the Gods. Carved on this enormous mountain was a message: ‘Heaven Prevails’…

After the Grand Descent, a name that was given to the descending of the mountain, the Three Great Sages made their ways to Mystic Mountain where they learned to harvest what we now call magic, establishing the Mystic Cults and eighty-one sacred shrines to help aid mankind with the cult’s mystic powers against the eternal fight to the death with demons.

- Description from Novelupdates

Her original self was a powerful jiangshi who had cultivated for innumerable years. However, when she attempted to unlawfully enter the world of the immortals, she was discovered by the Jade Emperor and thrown into the mortal world as punishment. Her soul then left her corpse, fusing with the body of the Motian Dynasty’s sixth princess. She didn’t even have a chance to fully comprehend her current circumstances before her maid unexpectedly ignored her mistress, even publicly provoking her!

“What? That weak and cowardly idiot who has neither her father’s love or mother’s favor actually mistook her older sister as her maid?! All the royal princes in the world loathe her?”

“Damn you! This old lady will let all of you understand why the flowers are so red!”

“Hey! Did you hear? That cowardly sixth princess unexpectedly snatched away the man that the eldest princess favored today!”

“How is that interesting news? That fourth princess who ran always ran amuck in the capital city is now confined to her bed now!”

The good-for-nothing counterattacks! The previously cowardly and incompetent sixth princess suddenly reveals her exceptional talents! She is full of radiant elegance, and unparalleled disdain!

She is driven by the desire to shed no more tears! However, if she had known what would happen later, she would have been better off acting stupid! She had calculated thousands, tens of thousands of scenarios, but had never calculated one where one day, her own prey would unexpectedly turn around, and ruthlessly bully her instead! Damn it, she still hasn’t sucked any blood yet!

- Description from Novelupdates