Reincarnated as the Baron's son: My Infinite Card Upgrade System - Chapter 7: Crystals

Depth-Dwellers are long extinct.All except for a single one..Waking up after being dragged by the pressuring tides, Cetas finds himself in the middle of an unfamiliar ship, greeted by a distinct group of pirates.Without any knowledge about humanity at all, he traverses the seas with the unknown band of pirates and learns about their culture and speech. In a world where 'Zeal' serves an essence for humanity's power, Cetas must learn to ascend the ranks to protect those that he cherishes.For when the mysteries beyond the fog arises, the Dreadspawns begin to wreak havoc, and the Leviathans rise up into the world..'Would Cetas become a 'human' worthy of saving those that he loves?'

William and his college class are ripped from Earth and thrown into Aethel, a world on the brink of collapse. Everyone gains incredible magical powers – except William. Mocked and underestimated, he’s an outcast among heroes. But William has a secret: an SSS-ranked skill that lets him travel to Aethel’s past. Learning lost magic from ancient masters, he’ll surpass his classmates and become the true savior Aethel needs. But can he overcome the dangers of the past and present to forge his own destiny? While others studied about the first mage, William could go back in time and see the first mage himself! While others dreamed of seeing a dragon, William could go back in time, hatch a legendary dragon egg and turn it into his puppy. While others used common materials to craft their items, William could go back in time and mine materials that weren’t find anywhere in Aethel anymore. Is it unfair? Perhaps, but William was not the type of person to not use the powers the universe gave him.

Perhaps it is the choice of fate. As a senior otaku, Qian Lingfeng got the “steel shell system”. However, when he swept the world with the system, became a local rich man, made all kinds of beautiful women, opened a harem, and realized the ultimate fantasy of thousands of otaku, he found that things seemed far from simple!
When the end comes, biochemical zombies suddenly come down, fierce beasts are in power, bloodthirsty zerg roam to kill the world, and human lives are comparable to dirt. Where will weak human beings go in this world? Is humanity going to be extinct? Or … can an otaku save the fate of the human race?

- Description from Novelupdates

[WSA 2025] To confront the threat posed by monsters and demons, humanity summons a hero endowed with a mysterious system and an unrivaled capacity for evolution. He becomes the last bastion of hope for mankind. However, one of his mistakes gives rise to a calamity far worse than the Demon King.This calamity is conceived in a dungeon, abandoned as a fetus by its mother, and raised by the Demon King himself. Upon the Demon King's death, all the restraints he had placed upon the creature are shattered. Thus, the hero's nameless son begins to lay waste to everything. The greatest calamity the world has ever known is born.