I am the first leviathan eater of humanity again:Futa - Chapter 1: After all these years

Ryan, a normal office worker who could be considered an extra in a boring world, did his job regularly and spent time here and there.He found himself, by mistake, being killed by a female reaper. Yet, the only thing he received as justice was a chance to transmigrate into a new body with his memories intact.Meanwhile, that female reaper faced a very small punishment: her powers were suppressed for ten minutes, leaving Ryan with nothing but a mocking smirk from the reaper as she ridiculed him for being a meager human with no life that belonged to him. He was left with no choice but to stand in front of the one who had granted such “justice” and watch the reaper laugh while turning to leave the place.In front of him was the reincarnation pool, and beside it stood the woman smirking at his misery while completely powerless for a whole ten minutes—there was no justice for him here. With his hands clenched, he decided that if he was really going down, he would take her with him. Swiftly tackling her, he pushed the reaper and himself directly into the reincarnation pool.The next moment he knew, he found himself being born as a extra disposal substitute of the Ducal Prince, destined to die at the hands of the princess in his stead.Soon enough, he understood that instead of some random world, he had been transmigrated into the last novel he was reading and a fan of—Invincibility Starts with Marriage and Having Lots of Children.[ Disclaimer: First POV for main charcter is mixed in chapters with Third POV of other characters ]( Disclaimer: There could be mistakes in the chapters, not because I am weak in grammar or something, but when one has to write 8K a day, the chances of things being left out are pretty obvious. So, if you understand what that sentence means, just ignore the minor mistakes, but if you want to point out grammatical mistakes, please do so. I will correct them as soon as possible.)

Eren Idril died as an old, decrepit, and piss-poor adventurer by the maws of a D-Rank monster. He had a lot of unfulfilled dreams and desires that couldn't see the light of the day after the light in his own eyes died down.

But fortunately for him and unfortunately for the world, that wasn't his end. Eren was somehow dived back in time when he was a mere teen, attending Lionheart Academy for adventurers.

When life gives him a second chance, Eren decides to exploit it to its fullest. Experience his vile deeds as he partakes in them without feeling the slightest bit of hesitation.

Zero – Where the End BeginsAfter 100 lives—lived as a king, a warrior, a scholar, a knight, and even a slave—he has finally reached the last.Life number 0.No rebirth. No second chances. Only death… or glory.Thrown into the most ruthless and enigmatic world he has ever faced, he must defy its crushing grip, where power dictates fate and survival is a battle against the inevitable. His ambitions collide with the weight of his past, driving him toward a relentless pursuit of absolute control.In Zero, you either carve your destiny… or vanish into oblivion.

As 21 years old Noah closes his eyes for what he thinks will be eternity, he wakes up in the body of a girl 7 years younger than him.Vasilisa, as she is known, is hated and mistreated by the people around her because of the Muddy Tongue curse which not only impedes her speech, but makes her magic unstable.This effectively makes her the harder than hard mode when it comes to reincarnation, and, of course, fate made her his “avatar” in this new world full of mechanics he only ever saw in video games.Despite this, Noah as decided…Whether as Vasilisa or himself, this time he will find a way to exist for the world.