Gimai Seikatsu - Days With My Step Sister - Chapter 42 - 6

“How did a perfectly fine magic world invested by ghosts?”Aya looked at the ghosts in front of her silently and raised her hand to cast a spell.She came to the past and wanted to change the tragedy written in the history books. But how did these ghosts come with her too?Ah, will she cause early destruction of the world?Uh......“Teacher, if I tell you that I didn't mean it, would you stop being angry?” Aya trembled when she looked at the man in front of her.She didn't meant to offend him!“Oh?” Her teacher looks back and smiled faintly. Did she think she could escape after provoking him?“Ah, ah, ah....”Aya swore that she didn't mean to provoke her young teacher. But it seemed that it was inevitable?QAQ

What happens when a scientist from a futuristic world reincarnates in a World of Magic and Knights? An awesome MC is what happens! A scientist’s goal is to explore the secrets of the universe, and this is exactly what Leylin sets out to do when he is reincarnated. Dark, cold and calculating, he makes use of all his resources as he sets off on his adventures to meet his goal. Face? Who needs that… Hmmm… that guy seems too powerful for me to take on now… I better keep a low profile for now. You want me to help you? Sure… but what benefit can I get out of it? Nothing? Bye. Hmmm… that guy looks like he might cause me problems in the future. Should I let him off for now and let him grow into someone that can threaten me….. Nahhh. *kill*-

Alternative: Leylin is transported from an advanced technological era into a medieval world— except there’s magic. Equipped with “only” his quick wits and an A.I. chip fused to his soul, he sets out to become the most powerful magus the world has ever known. In a land divided into the Light and Dark Magi, the weak can either be cattle or disposable slaves. Only the strong can determine their lives, and only they have the luxury for virtue. Yet strength is only a tool for Leylin, like any other. His goal, in the end, is his own.

The Strongest Magic meets the Mightiest Mecha.

I have stolen Golden Mechas from the deepest vaults of the most tightly guarded fortresses in the world.

I have personally destroyed more armies than the top three superpowers have in the span of the Absolute War - combined.

I burned down the terrorist megacity of Habon.

I was expelled from the Union of Heroes at a younger age than people are allowed in.

I have talked to Ancient Gods, loved women, and devoured mechas that would make superpowers cringe in fear.

I have faced demons head on in moonless nights others fear to speak of during the day.

I am deified in a thousand cultures, and labelled as the devil incarnate in the rest.

I am the Mecha Emperor.

You may have heard of me.

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Excerpt from Chapter 1

This is where it all began.

A junkyard.

Oh no, this isn't your clean, mechas-only junkyard that was the 'starting point' of many mecha geniuses out there.

I have seen and heard my share of rags-to-riches stories, and many of them claimed that they had started from 'junkyards' and slowly grew to be where they were right now.

From Zero to Hero, they declared.

You can do it too, they said.

As long as you work hard, everything is possible, they claimed.

I call bullshit.

Life doesn't work like that.

The story is about a a hitman, Who dies because of his own recklessness and transmigrates into a game he used to play after his retirement as a hitman.I'm not gonna spoil any further, but i might answer few of your questions.Is MC overpowered?Nope, he'll become strong over time and all battle he'll fight will be because of his effort and techniques.Is there magic and adventure?Yes! It have both magic like normal isekai with adventure and fighting with monsters and many other things. There are other important things like “Essence Stone” But let's talk about it in the chapters.There will be harem?Not really, He will be in contact with many beautiful female and males but one waifu but i haven't decided yet.All i can say is, give it a try, I'll try my best to make it worth your time.