I Am the Nanny of the Villain - Chapter 142:

In the city of Graheel, a small antique shop sits quietly mixed in with all the other shops. Its unassuming appearance is easily overlooked by many. However, this store and its owner has a terrible secret. A devil lives in that building. The owner of the store, John Li, an enigmatic figure whose origins and intentions are unknown. The desperate from around the world, often unknowingly, come to him in search of salvation.A red witch thinks the owner is an ancient creature, a white fox calls him a wizard of eld, a warrior believes him to be a spirit, and a holy woman declares him a god. This mysterious individual and his customers would stand at the center of a strange series of events. From the store owner John's perspective, he has no idea what's going on. He really was just an unlucky dude that got caught up in some crazy stuff.

Without noticing it, a man called Bill passed away, but then he realized that his life wouldn’t end that way and soon he was reborn as Billy in another world. Billy was already satisfied enough that he retained his memories, but the surprises didn’t end there. He was born with a weird power that granted him the chance to convert mana into experience points and transmit it to all sorts of things.

Things were looking pretty good until he noticed that he was born in an impoverished and rustic village that was facing their imminent extinction in the hands of creatures that he had never heard of before and other tribes that had all sorts of abilities. Before he could learn how even to crawl, Billy had to find a way to help his tribe. Otherwise, they will be annihilated before he can even become strong enough to stand.

Billy’s journey will be much different than he had imagined. Much farther away from Earth than he had originally thought, Billy will have to adapt to a new environment where his tribe is at the bottom of the food chain. Will he be able to grow up safely and try to change things for the better for his new family and friends?

In the foreign world, the martial artists dominate the world and the sword of the emperor controls the fate of hundreds of millions of lives! Long Yu, the number one killer on Earth, after dying, takes rebirth in this new world in an aristocratic family of martial artists but faces rejection because he is unable to practice martial arts.

- Description from Novelupdates

Time travelling from the majestic era after the Recuperation of Reiki, he became Kimura Kazuki, a 16-year-old high school student in Japan, one year before the Reiki Recuperation.

Tentatively, he set out to hone himself to the bone, burning candles at both ends to stockpile resources in preparation for the imminent Recuperation of Reiki. His goal was to be many steps ahead of all humanity when the time comes.

However, it seemed like fate had decided to play a cruel trick on him.

One year later, the Recuperation of Reiki… did not happen as expected.

- Description from Novelupdates