Rebirth on the Doors to the Civil Affairs Bureau - Chapter 55

A lecherous army special task force soldier from 21st-century Hong Kong is selected to travel back in time, choosing to go to the Chinese Warring States Period. Unfortunately, the time machine runs into an error during the experiment. With no foreseeable way to return to the present, he must use his combat skills and knowledge of history to thrive in his new life in the year 251 BC.

Nikolai gets bitten by a vampire and a werewolf on the same night. Their bites cause his hidden blood to awaken as the first hybrid. He grows stronger by devouring the blood of his enemies and lacks the weaknesses of both races.Despite this, he lives a normal life during the day. While at night, he explores a dark, hidden life, working for a spoilt princess and helping his obsessive friend. One is a vampire—the other leads a werewolf mafia group.Lost in this strange world, he finds help from Eliza, the strange pendant his mother created before she died. This helps him realise the world isn’t what he thought as he faces constant threats and danger from those who despise him.In this new world, his growth is rapid, and with endless possibilities, Nikolai fights for his life and to protect what he finds important while rising to the top.

Those people killed her grandmother, murdered her younger brother, trampled the people she deeply cared about, and even took her own life.

It was because she trusted her ambitious stepmother and half-sister;

because she mistakenly believed that womanly virtue is to have no talent;

because of her noble status and origin….This is what caused her death.

Buried in river water, Ouyang Nuan, gritted her teeth and spoke, “I, Ouyang Nuan was wronged in death. Even if it takes forever, I will become a devil, and in the next life, will not let you off!”

When she once again opened her eyes, Ouyang Nuan was sent back in time to when she was twelve years old. Around this age, her forehead was scarred, her brother fell into the water, and in three years she will be married…

In this life, she will try to change everything to guard and protect those she cares for from those with treacherous intentions. She will live a glorious life!

- Description from Novelupdates

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.