I reincarnated as an elf .......and married the yandere villainess. - Chapter 21:slight increase

In a distant future, the empires of mankind span the galaxy, and glorious Earth has devolved into a peripheral backwater.

In Shanjing city in the Asian region, Wang Zheng’s dreams of becoming a mech pilot are crushed when his college entrance exam genetic score turns out a pathetic twenty eight, barely above an animal.

To make things worse, people get the impression he attempted suicide after being rejected by the campus beauty.

Then the closest thing to a family he has, the old man in the book store across the road, goes missing, leaving him only a mysterious birthday present.

She has come a long way.

Orphaned, born a weakling, and being the infamous good-for-nothing of Azure Dragon Country. Gu Ruoyun was the shame of the proud Gu household. Falsely accused of a crime she did not commit, she was betrayed by her family and beaten to death by her own grandfather. But life took a fateful twist on that very day — she was revived.

Newly awakened, she is now the Master of an ancient treasure that resides within her body. Precious cultivation pills, treasures beyond her wildest imagination and spiritual beasts, all within her grasp… She is the apple of the eye of all under the heavens, including that of a mysterious, handsome man.

Now she only has one goal — to conquer the world.

- Description from Novelupdates

Song Lianhe transmigrated into a book, becoming the Villainess and legitimate daughter of the General Mansion, the Crown Prince's fiancée, and the female lead's stepping stone. Her existence was to use her ignorance and foolishness to highlight the female lead's intelligence and kindness; her repeated unrequited love also drove her completely insane, and in the end, she was tormented to death by the male and female leads working together...Song Lianhe transmigrated at the critical moment when the Villainess tried to drug the female lead, only for the plan to be cleverly thwarted by the female lead, resulting in the Villainess losing her own virginity instead.In a dilapidated temple, while “saving herself,” she said to the paralyzed man: “Don't worry, I will take responsibility for you...”Afterwards, the woman picked up her skirt and fled. The villain opened his eyes, his gaze filled with a cold and sinister venom: “I want her dead!”

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates