Rakuin no Monshou - Volume 1, Chapter 1: Iron and Blood

Xu Yangyi, an 18-year-old high school student, for the reason that his older twin sister eloped with her girlfriend on the wedding day, was forced to be the surrogate bride by his own father. As a result, he became the wife of the man who should have been his brother-in-law.“You’ve gotta look at me carefully. I’m a man.” Xu Yangyi glared at He Jingyan, who was still getting fresh with him though he already knew Xu Yangyi was indeed a man.“Man?” He Jingyan fiddled with Xu Yangyi’s face with his big hand and gave him a sly smile, “You look identical with your sister, so it doesn’t matter!”

Yang Feng somehow transmigrated into a different world and received a legacy of an ‘ancient high tech’ family, which does not directly raise his power, but gives him the technology to build things which are way more advanced than the seemingly medieval world.

But to build something you need resources and energy. To receive resources you need strength. To gain strength you need knowledge. To gain knowledge you… need strength? or a background? Or maybe a fully armed army of high tech robots who aren’t afraid of death?

But is this legacy really for him to keep?

- Description from Novelupdates

Riding out the apocalypse on a tropical island isn't exactly a vacation. When mana arrives on Earth, Coop finds himself isolated in paradise with only one real option to survive. He needs to claim a civilization shard and level up. Coop maximizes his chances by carefully selecting a class and committing to progression. He’ll need to grind thousands of monsters to compete on the system's leaderboards while upgrading his settlement to represent the factionless.