The Billionaire's Kept Woman - Chapter 348 - Crown Prince

Luo Yi, a high school dropout in his original world, was isekai’d into the world of the Witcher 3. Starting out as a weak boy named Roy in the village of Kaer, Lower Posada, he was determined to grow stronger, no matter what it took. The first step toward becoming a legend was to kill. And his first kill was… a rooster. ‘You gain 1 EXP.’ Of course, Roy had his own cheat system like all the other isekai protagonists. His first step to becoming a legend started now…

He is high above, the mysterious and terrible King of the Wild. With one glance, he can see people’s romances. He hates women to the extreme, but at his first glance of her, he dotes on her and spoils her.
She is a humble transmigrator, a miracle doctor who doesn’t care for the many handsome men around her. She only wants to become strong, to be worthy of that god-like man. But when she’s finally sure of her feelings, she finds out she’s already been married for years…
……
When wronged：
She uses strength to hit the big handsome iceberg-like man in front of her eyes. “People say that I’m not good enough for you, but it is you who is an old cow eating tender grass!”
A man seizes the main point and laughs like an evildoer. “This husband has to eat the grass to confirm if it is tender or not!” He puts out the red candle……
……
The world says：
The barbarian king has no heart and has no passion.
A pregnant woman very miserably thinks,” If he has no passion, then who is responsible for this big belly?”

- Description from Novelupdates

Fang Ze traveled to the world of psychic forensics and activated the detection system.

Since then, the world has gained a crime-solving wizard. In just one year, Fang Ze became the captain of the police force.

Suspicious disappearance cases, corpse dismemberment cases without clues, heinous vampire cases…

With his keen judgment, Fang Ze relied on the assistance of the system to grow all the way.

With the passage of time, Fang Ze suddenly discovered that this world seems to be more than just a psychic forensic doctor…

- Description from novelbuddy

Reborn as a sword, he lived for hundreds of years, and then he occupied the body of a 15-year-old prince.