One Piece: My Crew is from Other World - Chapter 397 – Gion Blushes, Ryuunosuke Meets Akainu!

I was the Pope.I had ten years to save the world from destruction.I came close to death many times, saved the world, and finally returned to Earth…[Warning! If you do not reach the target number of believers within 90 days, your system will be reset!]“…Excuse me?”“What?”“…I’ve come to tell you about the good news of our Lord.”

A ring-shaped bio-computer produced in 3009 AD, traversing the space and time onto Du Cheng’s head, a powerful intelligent program let Du Cheng tapped into high-tech knowledge in the next millennium.

——Commerce, industry, science and technology, Du Cheng will be leading the way, developing high-tech from the future, and making himself invincible.

——From an illegitimate child who was driven out of the family to the economic leader, creating a business empire, Du Cheng’s future is the road to the ultimate glory.

- Description from Novelupdates

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.

Wealthy, powerful and handsome; Gu Jingze is the cream of the crop in the entire country. Every guy wants to be him and every girl wants to be with him. His life is perfect… except that he has one tiny secret that keeps him from getting close to any woman—apparent impotency.

That is, until he wakes up in bed with a total stranger one day. The next thing he knows, he is forced to marry this stranger; a feisty and boisterous woman by the name of Lin Che.

Lin Che is an average girl whose only aim is to become a successful actress. Ostracized by her family and forced to become independent, she cooks up a scheme to attain her goal. But her plan fails and she ends up marrying this cold and seemingly heartless Gu Jingze. Not only that, she must now find her place in high society, where jealous women and devious plots lay abound – all while juggling her new career.

Two strangers under one roof: From the outset, they agree to stay out of each other’s lives, but he somehow always manages to appear during her moments of crisis. Slowly and unwittingly, Lin Che begins to find it difficult to imagine a future without him. Will their relationship grow, or is their marriage destined to remain just a contract?

- Description from Novelupdates