First Stygian Diviner:Apocalypse - Chapter 85 Grimoire

The end of the world is coming, the world has undergone great changes, and everything has changed. Plants, animals, and even insects, as long as there are living things, have mutated.
Become more powerful, and even evolved supernatural abilities, such as chickens and ducks that can fly to the sky, such as cats and dogs that can breathe fire.
But only humans, without any obvious changes, seem to have fallen from the top of the food chain to the bottom of the food chain overnight.
Any creature that can open its mouth to eat can treat humans as food.
But fortunately, this world has not completely killed humans. Gradually, humans discovered that they had the ability to cultivate compatibility with other creatures.
As long as it has a high degree of compatibility with some powerful mutant creatures, it can be used for its own use to achieve the purpose of protecting itself.
Fang He is a person who is very compatible with mutant animals, but it is also because of his ability that he has changed from the strongest to the stupidest.
Fang He, who was reborn, said, “Hmph, this time…”

- Description from novelbuddy

Takahiro Nao, a 25-year-old burdened by crushing debt and driven solely by his love for his struggling family, meets a tragic end—until a mysterious Goddess of Benevolence offers him a second chance: reincarnated in another world, and his efforts there will provide for his family back on Earth. Awakening in the body of Naoki von Blackmore, a disgraced “Failed Hero,” Nao is thrust into a realm of sword and magic, monsters, and war, tasked with the impossible mission of defeating the Demon King. With newfound powers, a shadowy past, and the weight of two worlds on his shoulders, he must battle not only relentless enemies but fate itself. Blending emotional depth, thrilling action, moments of humor, and a spark of romance, this gripping isekai adventure asks: how far would you go—and what would you sacrifice—for the people you love?

She was originally the young miss of the Marquis Estate, but became a peasant girl due to a mixed-up at birth.

Ye Zhen, a female Ph.D. in the Department of Mathematics of Huada University, changed her career to enter the entertainment industry in order to investigate the death of her birth father, Film Emperor Ye Yi. During her interview, she accidentally made CEO Rong Cheng Jue lose face in public. Yet Rong Cheng Jue, unlike what was to be expected, didn’t take old grudges into account and let Ye Zhen join his company. When everyone thought Ye Zhen would become Rong Cheng Jue’s personal secretary, she actually joined the entertainment department. After several twists and turns, Ye Zhen became an errand reporter for Rongcheng Entertainment’s “Treasures of Great Tang”.

Her colleagues’ bullying towards her, the pressure of changing career, and the many obstacles in her investigation all left her confused. Under Rong Cheng Jue’s silent guardianship, she didn’t forget her original purpose, overcame every obstacle, and eventually became an ace producer.

Ye Zhen and Rong Cheng Jue shared a common belief : no matter how bleak the hope is, how thorny and dark is the road ahead, they had only one thought in their hearts: to uncover the truth, and therefore bring peace to the soul of the Film Emperor Ye Yi.

- Description from Novelupdates