Mistress Of The Evil Forest - Case 101: Advent: War.

I do not own this imageHe was a swordsman beyond compare—cold, calculating, and relentless. A man who chased power not for glory, but to break the fate forced upon him. Betrayed in his final battle, he died with his blade in hand... only to awaken in a world not his own.Now reborn in the world of High School DxD, Nero carries with him a mysterious System that allows him to defy logic:— Steal and evolve Sacred Gears— Accept world-altering quests— Access a store that sells power itself— And shatter the limits of every universe he entersWith the power of his Void-Forged Blade and a will forged in war, Nero walks among Devils, Angels, and Fallen—but he kneels to none.As he joins Kuoh Academy, crosses paths with Rias Gremory and her peerage, and uncovers the secrets of the multiverse, one thing becomes clear:This world, and every world after it, will tremble beneath his blade.

Liu Man transmigrated from thousands of years ago to the modern world. Before she transmigrated, she was completely broke. After she transmigrated, she was still worried about her wealth. And so, for her to survive, she decided to start earning money by becoming a cyber star: trading and selling products, recording daily activities with her kittens, and showing off bits of her skills. One day she realized, that unconsciously, she had become one of the most famous celebrities.

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