The Fallen Hero Reincarnates as the Demon King's Son - Chapter 2 - 1 - Demon System

In each world, there would be the ultimate blackened female lead called Lin Xia, and each of them would’ve drowned in the light of their first love, aka the moonlight. Unsurprisingly, all of these moonlights were beautiful, attracting the love and adoration of Lin Xia, but in each and every world, the moonlight would eventually leave in the end, ultimately causing the blackening of Lin Xia’s fragile heart.

Years later, when the blackened Lin Xia finally fell for another woman, the special memories of the moonlight which was buried deep within her blackened heart began to fade, replaced by the light of the true soulmate.

And when the memories of the moonlight faded to almost nothing, the moonlight returned abruptly, only to be rejected by the moved-on Lin Xia. Filled with a crazed sense of jealousy, the moonlight began to destroy the new couples’ lives, only to be hated entirely and finally, crushed cruelly by the angered female lead.

And this is where the story begins, as a world-hopper, Ye SangSang would complete her missions in these worlds.

- Description from Novelupdates

The heck? l got reincarnated as a prince in another world!I have a system as well?[Choose class][Fiend Or Human Class?]Fiend Class.Choose the class from below.[Milf Manic][Blood Kin Copier][Plunder Sucker][10X Milk Man]Yeah I choose to become the strongest!On the other hand, why is my maid so cute?“My prince~ not there!”

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

I am merely a reviewer, albeit the products I review are slightly different. For example, I review quantum computers, artificial intelligence, anti-gravity mech armor, planetary engines, sublight colonial ships, stellar detonators, etc…