Tsuki ga Michibiku Isekai Douchuu - Chapter 400: First Joint Work

This is the story of a modern sailor who was accidentally reborn as a soldier of the Brazilian Expeditionary Force, and finally became the largest plutocratic family in Brazil by virtue of his foresight.

- Description from novelbuddy

Once upon a time in a modern city, a man died and was reincarnated into a body and a new mythical world.

This world holding many secrets, and wonderous things, but he possessed something that was highly regarded in terms of importance and usability: SPEED.

Join Noah on his quest to acquire great power, meet new people; while also discovering the many mysterious features of this new world he'll eventually learn to call his home.

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

Earth has once again descended into chaos with the rise of the Exiles—mysterious and powerful monsters intent on dominating humanity. In response, the defenders—the army—deploy modern weapons and the dwindling resources at their disposal, but soon find these measures ineffective as the Exiles begin to evolve.In this desperate situation, a group of innovative scientists develops a groundbreaking serum that grants extraordinary abilities to those who take it, resulting in the emergence of Beholders—meta-humans, ability bearers, and superhumans. It is about time for humanity to evolve alongside its adversaries.Sky, like his colleagues, receives the serum. However, instead of the expected powers, he acquires something far more stronger —a trait linked to disaster. Additionally, he must deal with its numerous side effects, which are rather extraordinary.