The Primordial Record - Chapter 1391: Physique Evolution.

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.

In the morgue full of Uchiha corpses, he opened his eyes…

A mysterious voice rang in my ear…

He looked confused: “Saving the ninja world, what’s the matter with me, the remnants of Uchiha?”

- Description from novelbuddy

[Dimensional Magic Cube's Instructions][1. The Dimensional Magic Cube can automatically absorb the energy that exists in the dimension. Once a month, it can randomly open a dimensional channel and perform dimensional travel.][2. The Dimensional Magic Cube has the ability to convert various powers from different dimensions, ready to be activated and used at any time.][3. There is a storage space inside the Dimensional Magic Cube, which can be opened and used at any time.][4. ...]This is the story of a man who once couldn't choose his own future but vowed to live for himself in this new life.Carrying the Dimensional Magic Cube, Riezel arrived in the world of swords and magic and wandered through different worlds, hoping to find a new beginning.===In a nutshell, a story about a man from Earth who got transmigrated into a fantasy world (original world that act as the main world) and has the ability to travel to various anime worlds to become stronger.Visited Worlds:1. Danmachi (Is It Wrong to Try to Pick Up Girls in a Dungeon?)2. Demon Slayer (Kimetsu no Yaiba)3. ...

A part-time job contract. He became the cold CEO’s imitation boyfriend. He merely wanted to earn a few small bucks and live a comfortable life, but a pity, he was in constant turmoil since then. Well, life had something else for him despite his wishes.“That… beauty, will there be an increase in wages for conversion from ‘boyfriend’ to ‘husband’?”

- Description from Novelupdates