After the Marriage, I Hid Commander Gao Leng Privately - Chapter 491:

A young man sat on a chair and looked out at the ocean. With one wisp of Spirit Qi, he could point anywhere on this vast and expansive world, pointing at any place that didn’t look right.

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.

The whole world mutated. Mysterious resurrections happened in real life. The Tribulation descended.

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