Monster Musume Harem wo Tsukurou! - Chapter 39: The first mock battle, New weapon, Ability of the heroes

In her previous life, she had misjudged people, mistaking enemies for kin. It wasn't until her body sank to the ocean floor that she had a sudden realization.Reborn seven years earlier, she grasped the Water-Repelling Pearl in hand, navigating unimpeded through lakes and oceans, ready to gather endless treasures. She vowed to carve out her own realm in the marine and collectibles industries.Before the conspiracies could even begin, she strategized every move. She would settle all past grievances—what was being a wealthy heiress? She would be the wealthiest of them all!

A man who was once called the world strongest agent ended up becoming a teacher after his retirement to train the new generation of agents. After many years of training his disciples, he is killed at the age of 60 by the ploy of a secret organization and was reincarnated in another world with all his past memories.Though he was surprised by the magic and the strange species of that world, he adapted very fast to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his tight discipline in order to reach his goal: resume his career as a teacher which he left halfway through in his previous life.This is the story of a man who based on the memories and the experiences of his previous life, became a teacher who travels through the world with his new students.

I exist in the darkness, disappear under the bright light, and will eventually devour the sun and turn into the shadow of all things… Known by people as the indescribable terror of darkness; the king of shadows; the dark day; the existence of the shadow of the world , is still just a somewhat special high school student, facing a weird death game…

- Description from novelbuddy

While reading a book, a sparkle of light disappeared. And, as it did, a message appeared.