I am, Flame-Chaser of Previous Era - Chapter 19: Vill·V?

Seven years ago, Shen Qianshu is impregnated with Ye Ling’s child in an accident.
Seven years later, the little boy becomes famous and is thought of as the nation’s son.

When he suddenly sees Ye Ling appear, he greets, “Hello, Daddy?”
Ye Ling watches as the little prince roars, “Where’s my princess?”
Just as Shen Qianshu is preparing to run with her son, she gets pushed down by Ye Ling.

“You can leave if you want, but leave me a princess first. Let’s have another baby!”

- Description from Novelupdates

Coming from one of the richest families in the world, everyone wanted something from her, and Cora felt she was never loved in all of her life. Desperate to find true love, Cora got married into a pauper she took a liking to and secretly helped him rise to the top. She pretended to be disabled and poor in order to prove to her family that he was a good man, but on the day she planned to reveal her identity to him, she found him cheating on her on their bed.Filled with so much rage, Cora vowed to crush him piece by pieces.Being this heartbreak. She vowed to never love again as well, but it felt like the world was waiting for her to be single because the moment she became single.Over a Battalion men wanted to marry her.

Aaron, a wildlife biologist, became a military strategist right after a global war between nations began.He never wanted to participate in the war but he had to, because he wanted to continue his studies on endangered species the moment the war was over, but to his surprise, everyone in his unit were killed, including him, and the next thing he knew, Aaron woke up in the body of a young noble having a similar name to his.However, he also noticed he had awoken in a world different from Earth.In this world, demonic beasts ran rampart with only one thought in mind, causing them to feed on anyone they see, be it humans, elves or even magical beasts as well.During his first encounter with a magical beast, Aaron awakened a system which allowed him to bond with magical beasts and to obtain terrifying abilities from these bloodcurdling magical beasts, so he used his experience as a wildlife biologist to help make it easier for him to bond with these beasts.However, Aaron also noticed he could evolve these beasts if their loyalty towards him had reached a certain level, so he vowed in his heart to grow strong enough to protect those he cared about in this world with the hope of living a happy, peaceful life where he'll be able to focus fully on his passion as a wildlife biologist.

Waking up, Kim Hajin finds himself in a familiar world but an unfamiliar body.