Demon King: Hero, don't run away! - Chapter 302: To be honest, it’s hard to say.

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

She, the world's chief doctor of the 21st century, the legendary overlord of the medical world, was killed and her soul transmigrated…She, the useless miss of the Windcloud Empire, was ugly, silly, and obsessed! She died in her own sister and fiancé's hands…When she reopened her eyes again, she had the soul of the strong but the body of the weak…When she became her, her fate would be rewritten and a miracle would appear…This was a story of a two-faced person meeting another two-faced person. With pure hearts, they would end up together.

A sudden and unprecedented event occurred and took place on Earth.A fissure instantly appeared in the clear blue sky, revealing a void devoid of any light beyond, instantly covering the whole planet, leaving no Life, no Hell, and no Paradise behind...Hence the start of a new chaos and a great beginning of life devoid of any hope began.In this apocalypse and lawless world without any limits set upon its beings, a silent dark wisp took form.A wisp that was bound to become the Horror of All was born...“Wait… I’ve become a Ghost?!”

Huang Dan’s pain nerve is innately different from the ordinary people. A little tore in his skin can cause him to sweat all over his body painfully to the point of him unable to make a word out.

Somehow, he began to cross world, following Mr. System to do the tasks…

In the first world, Huang Dan realizes what it means to die painfully and to live to die again.

TL’s summary:
MC suddenly transmigrated and is bind to a system, requiring him to solve mysteries. Born with a higher degree of pain sensitivity, he met different people in the different worlds and learns what kind of emotion smiling is.

- Description from Novelupdates