Valkyrie's Shadow - Chapter 8Birthright: Act 5,

A con-man and policewoman that are legends of their respective professions suddenly die, then are reincarnated and return to the Tang Dynasty of ancient China as little kids.

Accepting their second chance and forced restart, they choose to use the modern knowledge and specific talents that they have in their previous lives in order to live comfortably in this new life.

- Description from Novelupdates

Xiao Luo and his girlfriend had been in love with each other for four years when she proposed a break up. Because of this, Xiao Luo sped his car in the night and ended up in a car accident. But it was a blessing in disguise as he unexpectedly fused with a high tech system that originated from a universe hundreds of billions of light years away. From this moment on, the entire world started to run amok.....

The King Of Assassins was a monster that reigned over the world of hitmen for long years. He was the absolute peak that no other being could reach. His name reached the ears of every powerhouse in the world and sent shivers through every human.

Yet, his legend came to an end suddenly when he died in unknown circumstances.

However, instead of disappearing forever, he was given another chance in another world by the goddess of reincarnation. It was the world of an old book that he read back in the time. A world where everything was possible, where humans could reach new heights that were impossible in his old life.

But, this place didn't seem to be normal as it carried a huge surprise that will make his journey seem all the more interesting.

The Goddess of reincarnation wasn't as holy as anyone would think. She was nothing but a twisted being who found a toy to play with. The goddess manipulated the world that he was going to and changed all the heroines into these twisted beings that fit her character. They were all now harboring this unhealthy obsession toward him and trying with all their powers to take him away for themselves.

The eldest daughter of the Li family is beautiful and sassy, ​​she took space materials to flee famine, and after going through many difficulties in war, disease and epidemic, she united with her family to regain the glory and harvested a beautiful boy.

- Description from novelbuddy