Moto Sekai Ichi'i no Sub-chara Ikusei Nikki - Chapter 14: Royal Magic Academy

Raised by a league of assassins and trained for thirteen years, Shan Yue was seventeen when she took the throne of best assassin, becoming an untouchable legend amongst assassins.

Despite being legendary, she put her faith in the wrong people and was killed by her own league’s betrayal. However, while Shan Yue thought her death was assured in the violent explosion, she was surprised to find herself reincarnating into the body of a useless female student.

Forget how pudgy and dim-witted she was — she seemed to get into fights every day! Her original body’s sister sneered, “Fatso! All you do is eat… and look at how ugly you are! You really embarrass me!”

Fat? Ugly! Shan Yue started a daily training regiment, rapidly slimming down and becoming a ravishing beauty! Her original body’s mother snapped at her, “How did I give birth to a child as stupid as you?! Always last place in school — you embarrass me!

I should have strangled you right after I gave birth to you!” Stupid?

Last place in school? Shan Yue lifted a finger, and the principal of the top school in the capital personally visited, offering a transfer to his school. Elite hackers, doctors, mercenaries, math geniuses…

All of them were now vying for her attention! Though she managed to get the chance to become normal after going through so much, she accidentally become a big shot again, even finding herself a two-faced bigwig for a husband! Shan Yue: I just wanted a quiet life, but my abilities prevent that. Sigh…

Wang Cheng: Boss Chu, I think my mom will not agree two hundred percent with our affair, so I have a once-and-for-all proposal, do you want to hear it?

Chu Yifeng: Let’s hear it.

Wang Cheng: It’s very simple, why don’t we break up and not worry about anything?

Chu Yifeng: What you said is quite reasonable, but we can discuss this matter further in the bedroom.

Wang Cheng: …I’m just kidding. Look at my sincere face. How could I break up with you?

Chu Yifeng: It’s too late.

- Description from Novelupdates

In a world where ancient magic has been resurrected. Atlas, an orphan from Earth, finds himself transmigrated into the body of a child and possesses the rare Void Magic. Harboring such power, he’ll walk the path of becoming stronger and stand free in the sky above all existence!The tale of the Legendary Void Walker is about to begin!The cover doesn't belong to me! The title was done by TiramisuAndCoffee!

In short, MC inadvertently created a world, but as the creator of the world, he did not know the world at all. He should have lived here like a fish in the sea with some plug-ins that MCs always have. But now he is even stumped by the bugs in the instant world. Luckily, in this world he has found his shadow guard, or his lover? So the daily adventure is getting not so boring…

- Description from Novelupdates