The Charm of Soul Pets (WN) - Chapter 12 - Grind, Train, Improve

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

16 years old-- most boys would be falling in love, as their hormones all rise to unprecedented levels. Most boys at Riley's age would have dreams; dreams that will slowly grow into passion. Riley, however, at age 16... killed the world's number 1 superhero.

In fact, Ling Yun was the son of a wealthy businessman. But one day, his mother finds out that her husband is having an affair with his secretary. And after that she decided to divorce her husband, but at that time she did not realize that she was pregnant with Ling Yun.

After learning about her pregnancy, she decided to move to another city. And since then, their lives have been up and down. Because of the economic crush, and also his mother's health was getting worse.

He decided to take the 'Dark' path, which led him to near death. But just as Ling Yun was nearing his end, he heard a little girl's voice asking him.

“Do you want to live?”

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…