There was a mage called ‘The Lone Demon King’ at the frontier.
He was just a creature that never grew old, but he was loved by the villagers as something of a guardian deity.
However, he was destroyed by a magic organization that sees his existence as dangerous.
200 years later, he is reincarnated as the second son of an aristocrat and obtains the strongest magic power.
“Let’s pretend to be a human this time”
However, being a human lover, he didn’t particularly think of revenge and has decided to pretend to be human in this life.
In his past life, he was the guardian deity of a region, and in this life, he’s a local aristocrat, but he does not know common sense. He doesn’t know how to take it easy.
As the second son of an aristocrat, he is loved by his family and friends, and while he is regarded as a master of magic in the magic guild, he becomes an ‘Immortal Mage’ behind the scenes.

Webnovel Raw: https://ncode.syosetu.com/n9450fl/

Combining reality with a gaming world where ferocious beasts roam freely, filled with numerous mysteries and dungeons. In order to defend against the onslaught of these beasts, everyone undergoes class transfers and crazily levels up. On the day of his transfer, Lu Fan becomes a hidden class – Dragon Tamer. However, due to the immense strength of dragons, it is deemed impossible for anyone to tame them, earning Dragon Tamer the reputation of being the most useless class. Fortunately, he awakens the Super Treasure Map System. As Lu Fan, with his mighty dragon, sweeps through everything, the entire world trembles.

From MangaHelpers :
High school student Misumi Makoto is called into a fantasy world by the god Tsukuyomi, in order to be a hero. However, powerful others in this world aren't as thrilled to have him there, and they kick him to the edge of the world just as Tsukuyomi declares that he must leave Makoto to find his own way. Now it's up to Makoto to find his own way.

Born as the Thirteenth Prince, Noah was originally in a position removed from the imperial succession, so he freely passed his time in the fief granted to him.

However, the Crown Prince died before the Emperor. The imperial succession would be fairly contested among the remaining princes.

Noah, being the strongest despite living freely, overwhelmed the other princes and eventually became the Emperor with the most power in the world.

Olivia is picked up by a death god, Z, deep in the forest as a child and trained by him in combat for reasons unknown. One day, Z disappears, leaving behind a letter instructing Olivia to head to the Kingdom along with a sword bearing the qualities of a death god's weapon. Thus, the girl lacking in common sense, knowledge, and normalcy sets off to join the army.

Leon, a former Japanese worker, was reincarnated into an “otome game” world, and despaired at how it was a world where females hold dominance over males. It was as if men were just livestock that served as stepping stones for females in this world. The only exceptions were the game’s romantic targets, a group of handsome men led by the crown prince.

In these bizarre circumstances, Leon held one weapon: his knowledge from his previous world, where his brazen sister had forced him to complete this game. Leon, who really just wants to to live as a shut-in in the countryside, uses that knowledge to raise a ferocious revolt against the women and handsome men.

From MangaHelpers:
29-year-old programmer Suzuki Ichirou finds himself transported into a fantasy RPG. Within the game, he's a 15-year-old named Satou. At first he thinks he's dreaming, but his experiences seem very real. Due to his use of a 3-time-use special power (meteor shower), he ends up wiping out an army of lizardmen and becoming very high level. He hides his level and plans to live peacefully and meet new people, though developments in the game story (like the return of a demon king) might get in his way.

"THE NEW GATE", an online game that trapped its players and turned into a death game, was now releasing the thousands of players that had been dragged into it, thanks to the efforts of Shin, one of the most powerful players. But after having defeated the last boss and freed everyone, he was swallowed up by a strange light and found himself inside the game world 500 years in the future and unable to leave.

As the master of the School of Unholy Arts and as the undefeated Unmasked Demon, MookHyang unfortunately falls to a strange fantasy world by the magic of his enemies (School of Blood Arts). In the new world of elf, sorcerer, knight, and dragon, MookHyang’s adventure of finding a way back to his old world (Murim) unfolds.

Used to be a Hero, and before that a Sage, Lex has reincarnated. Again. This time he just wants to be a NORMAL adventurer…

The protagonist fell asleep while playing an online game. However, he awoke in a strange world with his game character’s appearance. In a state of shock, he noticed that he was equipped with nothing but his strongest weapon and armor. To make matters worse, our hero’s appearance was changed by the special avatar skin 『Skeleton』 when he enter this new world. The protagonist wanted to live without drawing attention, but he got acquainted with the dark elf Ariana and received her request.

From LHtranslation :

In a certain world, there was someone who excelled in magic combat, people called him 『Sage』. Seeking the strongest combat art, he devoted himself to research every magic and combat arts in existence. And the conclusion he arrived at was very cruel, 『My body is not fit for magic combat』. Yet he didn’t give up. He sealed his own soul with a magic art, and was reborn in a far-off future. And the magic theory in the completely changed world he saw there was of unbelievably low level.

There has been much conflict between the races of the 'Humas', the 'Gabranth', and the 'Evila'. To combat the 'Evila' race's Demon King, the kingdom summons five high school students from 21st century Japan who have the power of Heroes.

However, only four out of five of those students had the status title of 'Hero'.

Okamura Hiiro was summoned by accident since he sat near the other four students in class. Unlike them, he did not have the title of a 'Hero' but instead he had the title of 'Word Master' and 'Innocent Bystander'. Seeing through the 'Humas' kingdom's deceit and insanity, Hiiro decides that he has no wish to partake in their selfish war. Leaving the castle, Hiiro decides to join the Adventurer's Guild and does whatever he feels like. Who knows? Maybe there is some merit to being a 'Word Master' and an 'Innocent Bystander'.

Amamiya Hiroto is unlucky. His life consisted of misfortune after misfortune, culminating in an unlucky death during an incident on a school boat trip, trying to save a girl he barely knew. After death, he met a god of reincarnation who requested that the hundred or so dead passengers - one of them being the girl he tried in vain to save - be reincarnated into another world.

Yet a series of unfortunate events forced Hiroto to reincarnate with even less luck than before, starting with nothing but a tremendous amount of Mana. His second life, far worse than his first, came to a cruel end.

However, upon meeting the god a second time, he was informed that there would be yet another reincarnation - one that had already been set in motion and could not be stopped. Not wanting Hiroto to endure a third life filled with suffering, the god cursed him before he was reborn in the hopes that he would either die quickly or commit suicide.

Hiroto was reborn once more as a half-vampire, half-dark elf. A dhampir. Not wanting a fourth life, he is determined to live this third life with the only things remaining from his previous lives - Death Magic and his enormous Mana pool.

A magic nerd's life came to an end after a dreadful encounter with the nobles who ended his life with a powerful spell. His last wish, being able to study and master more magic, has been answered when he was reincarnated as Saloom Lloyd, the 7th prince of Saloom Kingdom. Now he'll be able to perfect his magic as he pleases...

When Theodore was dropped into a waterway by his half-brother, he suddenly recalled the memory of his past life. He had been a Japanese citizen known as Kirishima Kagehisa, placed inside VRMMO character he had made in Break Force Online. "Theodore" is a Combat Mage that Kagehisa played within BFO, and he realized his skills were progressing well even in this other world. Theodore, who had lightly brushed off his half-brother to make his own place in the world, had ventured off to the large labyrinth existing at the Boundary City, Termuilles.

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 students.

After losing his girlfriend to a brave hero, Toru is expelled from his S-Rank party. With a feeling of sadness and pain in his heart, he defeats a demon he meets outside the city, and his ability [to save experience] is broken! Toru becomes level 300 in the blink of an eye! With this power that far surpasses that of heroes, there is nothing that can stop him. Kaede, a slave he met on his journey, forms a group called the "Mangyu Brigade", and easily completes dungeons, acquires the legendary sacred weapons, and thanks to his skills, his friends level up easily! He rescued a countess who was attacked by bandits on the road, and befriended a legendary beast. Oru's journey continues at a leisurely pace, as he repeatedly encounters various people along the way, while his former party of heroes are deprived of opportunities to play an active role and fall into decline. This is the beginning of the life of a 300 level warrior!

Original Webnovel: https://ncode.syosetu.com/n9483ge/

Very ordinary company OL (Office Lady), Azusa Aizawa, died from overwork.

For that reason, I decided to live a slow life in a house in the mountains as an immortal witch with the figure of a 17 year old.

The main source of income is to defeat slimes inhabiting the area to acquire magic stones. I sold these at the Guild in the village. Besides that, I made medicinal herbs, became known as “The Witch of the Highlands”, and lived with respect and trust.

However, as a result of continuing to beat slimes for 300 years, the experience values accumulated too much, and I unknowingly became level 99, the world’s strongest witch .

The level 99 witch now works together in the village with her dragon-girl apprentice in moderation, while helping everyone in the village.

Banaza, who got summoned to the magic kingdom of Cryroad as a Hero candidate, due to having only the abilities of only a regular citizen, got treated as a disqualified Hero. He, who originally was supposed to be returned to his original world, due to the magic kingdom's mistake, became unable to return to his original world, inevitably has to live in this world. That kind of person, the moment he became Lv2, acquired all skills and magics, and transcended into a super cheat with all ability points broken through the limit! Even so, he does things at his own pace with an easygoing smile.