MTL - The Little Merman - Chapter 3

Some say reincarnation is a blessing, but for me, it's a dreadful curse. Cursed with endless reincarnation, I've been reborn as a villain 137 times. And all 137 times, I've been toyed with and killed by heroes who are far more cruel than the said villains... If I can't win no matter what I do, then I'll crush those so-called heroes at their very roots. - Quality Fan Translations, Made by Fans for the Fans - Villain Takes Over The Academy

“With my knowledge, give me a fulcrum on which to place it and I shall move the world!”

…

Sorcerer Continent—a world where sorcerers exist. Wielders of arcane knowledge. Masters of all elements. Sovereigns of space and time. These sorcerers governed the world with their unrivalled prowess. One day, a young man awakened into this world with his past forgotten and no place to call home. Follow along as Glenn, by relying on his luck and wit, tries to survive and advance in this unforgiving world. Entangled within the machinations of fate, political schemes, power struggles and wars, he forges his own path and creates a place for himself.

- Description from Novelupdates

The world where the Hero and the Demon King continue to oppose each other. The grand magic from the Hero and the Demon King cross over worlds and exploded in the classroom of a certain high school.

The students who died in the explosion will be reincarnated in a different world. The protagonist, who had the lowest reputation in the class, was reincarnated into a spider. Nevertheless, she adapted quickly to the present condition with strong willpower.

This is a story of she who has become a spider trying whatever she can to live.

A reputation as ‘The Most Feared Gunslinger In the West’, and the Law hot on his heels, Henry Morgan had lived a full life. So when it all ended with a gunshot to the back of his head, he was quite ready. He embraced death… He embraced his end.Except it wasn’t the end…Some mysterious [Powerful Forces that be] wrenched him out of the world he knew and deposited him into the body of a version of himself in a Parallel world. A world where something as ‘impossible’ as Magic apparently exists.These [Powerful Forces that be] went a step further by granting Henry a System and issuing him strange prompts and Quests that send him down a road of Adventure and bloodshed all so he can etch his name in history and show this world and its many ‘wonders’ just how deadly a Gunslinger can be…