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/

Saitou is an ordinary handyman that gets transported to another world where his skills are very useful. He starts to really understand what it means to be needed.

From Nyan-Nyan Rampage:

"The final arc of the story begins...

When Takao Osugi receives the mysterious "Universe of the Four Gods" book from his mentor, Einosuke Okuda, he does everything to keep it away from his young daughter, Suzuno. But when disaster strikes Tokyo, can he still protect her from her fate?

Shortly after the tragic finale of Genbu Kaiden, young Suzuno Osugi's tale as the Priestess of Byakko beings to unfold!"

The setting is a certain kingdom. In order to save the kidnapped princess of the kingdom, the Kingsguard squadron challenges the "Dragon Tower," a gigantic structure floating in the middle of the sky, but they are blocked by powerful demons.
A provocation is made by a neighboring village to replenish the injured personnel, and when a young man is sent to the tower, the wheel of fate begins to turn.

Tale of sword & sorcery and labyrinth exploration begins!

Beryl Gardernant is a humble sword master who runs a dojo in the Reveris Kingdom.

He had come to terms with the limits of his strength and was living a leisurely life in the countryside.

However, his life changes drastically when Alexia, one of his former students, suddenly visits him and tells him that she has recommended Beryl to be a special instructor within the nation’s Knight Order.

He is reunited with his former students who have become big-shots such as knight captains, top-ranking adventurers, and ace magicians, and he is kicked out of his family’s dojo.

Turbulent times were ahead of him.

Beryl was happy that his former disciples adore him, but he is also humble about the fact that he is not very strong.

However, while he wasn’t aware of it, he was the owner of an unparalleled talent.

Unconscious of his power, Beryl is surrounded by ex-disciples who know of his strength, and gradually makes himself known to the world, all the while remaining rather unaware of all of this.

The hero, Fried, confronts the demon lord with his student, Lyle. Fried killed the demon lord after a ferocious battle. “I'm going to put an end to this war!” Just as he was about to finish off the demon lord, he is betrayed by his student who attacked from behind. Fried, who was supposed to be dead, wakes up next to a demon girl who calls him the demon lord for some reason. It seems that Fried has risen as the new demon lord and will now have to protect the demonkind under his command while fighting his former comrades

Webnovel Link: https://ncode.syosetu.com/n0087ep/

This is the tale of a man who had mastered how to “parry.”

“I have no talent at all…”

At the age of 12, a young boy named Noru had decided to train himself in the mountains after being rejected by the capital’s official training centers for being “talentless.” He believed that, with enough hard work and effort, he could one day become like the protagonists that populate his childhood stories. Full of determination, he would practice every day with his makeshift wooden sword, endlessly repeating the only sword technique he knew—“parry.” The hours turned into days, the days turned into months, and the months turned into years. Eventually, he had trained this one skill to such an extreme that he could snap a thousand branches with it. However, no matter how hard he tried, he couldn’t get the desired result, he couldn’t learn any new skills required to become a real adventurer. It may be time to let go of his dream. But he couldn’t. Not just yet. Knowing this, he returned to the capital again.

This was a man of endless dedication, a man who used that dedication to become one of the strongest in the world. The only problem is, he didn’t know it yet.

Han Lee, a graduate student.

Born as the youngest member of a famous magic family in another world.

He vowed never to go to the place where the word 'school' was written.

The place where the resolution was headed to the colorless was the notorious magic school 'Einroguard'.

Self-sufficiency is the default, monster appearance is an option, and professors are all the same!

The salty school life that I have never seen before begins.

Can I... graduate safely?

A world where machine civilization has perished and immortal monsters called "Monotsuki" are rampant. Isana, a girl born in a remote village, meets a mechanical person who lost her memories and looks exactly like her sister, who should have disappeared in the ruins she wandered into. Convinced that "My sister is alive," Isana gives the mechanical person the name "Hime" (princess) and together they set out on a journey to find her sister.

The Law of Justice Online, also known as LJO, is the hottest new VRMMORPG of the season, and office worker Yuta Sasaki is one of the lucky few granted access to the official launch. After some careful research, Yuta is chomping at the bit to start his virtual life as a Tamer, a class that harnesses the powers of wild monsters. Luckily, upon building his character, Yuta manages to land not only his chosen class, but a heap of bonuses to boot! He soon finds, however, that his abilities are not all they're cracked up to be, and that the talents of the rare first monster he is granted lie not in combat...but gardening! Already well behind the other adventurers, and facing a long and slow progression path ahead of him, Yuta is left with two choices—start over from scratch, or make the best of what he has been given. For Yuta the choice is obvious: When life gives you manure...start up a farm!

A space series about a protagonist who continually fights against all the aliens who are trying to take his life.

This protagonist, the most demonically strong exorcist. Akira the S-class exorcist sent from Germany to investigate a paranormal event in a certain city in Japan. He shoots creatures from other worlds with his beautiful exorcist partner Chikage.

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.

As a child, Thorfinn sat at the feet of the great Leif Ericson and thrilled to wild tales of a land far to the west. But his youthful fantasies were shattered by a mercenary raid. Raised by the Vikings who murdered his family, Thorfinn became a terrifying warrior, forever seeking to kill the band's leader, Askeladd, and avenge his father. Sustaining Thorfinn through his ordeal are his pride in his family and his dreams of a fertile westward land, a land without war or slavery... the land Leif called Vinland.

Note: Was nominated for the 2008 Manga Taisho award. Won the Grand Prize in the manga division of the Japan Media Arts awards in 2009. Won the 36th Kodansha Manga Award for Best General Manga in 2012.

In the Great Orient, lies the continent called Rodenius.

One day, an unidentified flying object arrived at Qua-Toyne Principality’s airspace. The unidentified flying object defied the Principality’s common sense. But that unidentified flying object was just a harbinger of something even more shocking.

Far to the eastern sea, a group of islands suddenly appeared. The country of the islands called itself: Japan. According to them, their nation had been transported to another world.

Now finding themselves separated from their old world and must survive in the new one, how will Japan interact with the native countries of this world? Will they greet her as a friend or as an enemy?

This is a story of the country called Japan as it was engulfed in the chaotic storm of the world.

Basically, the Japanese version of Island in the Sea of Time. For clarity: The summoned area of Japan are the four disputed Kuril Islands, Japan Home Islands, and Ryuku Islands.

When a child is born, they are granted a [JOB] by the goddess of light. Unfortunately, Ain is granted the unfavourable job of an [Appraiser]. All he can do is appraise materials, and so he is treated horribly by his own party. Then, one day, he happens to come across an S-Ranked tree hidden in a dungeon. Following this encounter, Ain slowly but surely changes...

Links:
Web Novel: https://ncode.syosetu.com/n5242fx/ (Japanese)

From Manga Updates: A very popular early work from Kinoko Nasu from the Tsukihime & Fate fame, the Kara no Kyoukai universe has meet great success as an animated film adaptation, novels and radio dramas. Kara no Kyoukai depicts a world were the true dark nature of the human being is being reviewed and exposed by shocking and ruthless events, and in the center of it all we have Ryougi Shiki, the true heir to the long lived, wealthy and mysterious Ryougi clan and Kokuto Mikiya, a would be normal high school student if it wouldn't be for his amazing deductive & investigative progress. The moment Kokuto and Shiki meet is the moment that the wheel of fate started to turn, however is this fate moving forward naturally of it's own accord, or is it all being orchestrated from behind the scenes by an enigmatic persona? Only time will tell.

While on a regular school day, Tsukuru along with his classmates got transported to another world. However, at the other side of the summoning there was a hero's auction, where each nation would bid for the heroes to defeat the demon kings of each territory. While his classmates received cheat jobs and got auctioned quickly Tsukuru got the useless job "Chef", as no nation bid for him, he got thrown out through a transfer gate. At the other side of the gate was a territory dominated by strong monsters...
As he manages to survive the monster's attacks while nearly dying, Tsukuru goes forward on the path of becoming the strongest!

"Yukio... I'm going to make a friend." A shy boy named Tetsuo. The only thing he had was a giant robot named Yukio. They became "saviors" in the fight against the galactic monsters coming from outer space. After the final battle, Tetsuo returns to Earth for the first time in ten years and witnesses an astonishing world. It's a frozen Earth (named Snowball Earth), where the entire land is covered in snow and ice, being turned into a deadly world! What happened to the human race? And will Tetsuo be able to fulfill the promise he made to Yukio?

When an entire bus of people are summoned to another world, Souma Nagi doesn't go along with the idea of being a Hero like the rest. Thus he leaves the palace and starts his life in another world with his ability to restructure skills. Based off the Light Novel by the same name.