Moto Sekai Ichi'i no Sub-chara Ikusei Nikki - Chapter 6: Essential Skills

After getting forcefully reincarnated into a world of an otome game he has no clue about, the protagonist is then killed and brought back to life by the prideful villainess with one desire.

To rule the world.

As the ruthless girl’s Eternal Servant, how will he dodge the fate that the game system has in store for him?

Through a mysterious portal, Chen Jin arrived at this strange place – a post-apocalyptic world where civilization had been destroyed.

Consequently, he found –

A piece of metal scrap
A robot trash collector
A battleground
A city
A ton and more of gold
A copy of high-tech documents
A…
In short, Chen Jin found a planet.

- Description from Novelupdates

As a boss with space plant abilities in the apocalypse, Lu Yao once traveled to the future, became the director of a nursery school that was about to close down, and became a rare animal human on the verge of extinction.
The food she made at random can cure the genetic disease of the cubs in the welfare home. She punched the cubs’ scum fathers and scum mothers, and kicked the remarried families who abandoned the cubs.
It is such a good kindergarten successor dean, who is attracted by that single cool imperial marshal!
Since then, the barrage in the live broadcast room has become:
Imperial Citizen A: Dean A, I really want to marry.
A certain big black dragon: Shut up! This is your marshal’s wife!
CP: Dean Lu Yao, who is extremely protective of short-sightedness and loves cubs, X the imperial marshal Helanjia who loves Shang Yunxi more than cubs
Brief: There are no bad cubs, only bad big ones.

- Description from novelbuddy

Rex was an ordinary salaryman, resigned to a dull life of monotony in a towering megacity. But his world shatters when he’s conscripted by Nexum Dynamics, a ruthless megacorporation, and thrust into a brutal war for a barren, alien world. The planet holds unimaginable riches, but it’s also swarming with the Krhyssari, an insectoid race that dominates the surface with their hive-mind precision and relentless aggression. Amid the carnage, Rex had an extraordinary encounter with Cleo, an ancient AI, a survivor of a long-extinct civilization. Cleo isn’t just an artificial intelligence; she’s a consciousness imbued with memories of her people’s interstellar empire and equipped with advanced bio-nanotechnology. Offering Rex a new purpose and unmatched power, she transforms his fragile human body into a hybrid of living metal and flesh, making him the ultimate weapon. But Cleo is more than a tool of war. As she journeys alongside Rex, her cold, logical algorithms evolve, shaped by his humanity. Together, they form a bond that transcends the boundaries of man and machine, discovering love in the midst of chaos. As Rex and Cleo fight for survival, they uncover a shared ambition, to rise as intergalactic overlords, uniting or conquering the galaxy.