Naruto: Dual-Pupil Uchiha - Chapter 142 : Itachi and Shisui’s Decision!!:

Waking up in the body of a 6-year-old boy a few years before Cintra is destroyed, Madara receives a system that gives him the ability to gain the powers of Uchiha Madara.[The peak of Uchiha Madara's system is before he becomes the ten-tails jinchuuriki.]The system's percentage does not stop Madara's power, but rather the system's release. After all, I don't want to see a character who goes around killing everyone from the beginning of the story.

Sa Bina was on her way to write her SAT when she suddenly finds herself in a strange world. She is sent to be the old emperor’s concubine, but on their wedding night, the emperor gets murdered by no one other than his own son and the heir! To survive, Bina makes a deal with beautiful but deadly Lucretius and her life in this dangerous kingdom begins.

A data loving young man from Earth has an accident which transports him to a dark land filled with terrifying creatures and magical powers. Fortunately for him, he has a Biological Assistance Chip to ease his path. However, things in this bizarre and strange world are not always as they seem, and, though it is a tremendous asset, the chip doesn’t always work as expected. With all of the crazy creatures and magical mayhem around him, one can only wonder what the future holds for this young man…

- Description from novelupdates

“Let the world burn… if that’s what it takes to keep them from stealing what’s mine.”William Knox, once hailed as the brightest inventor of the century, dies with his heart corroded by betrayal. His daughter and closest friend stripped him of everything—his legacy, his empire, his future. But death wasn’t the end… it was only the beginning.He awakens in a strange world, ruled not by science, but by magic. His body is no longer his own. His soul is bound by a dark contract, and his mind is still tethered to his past—thanks to a newborn AI and the last working prototype of his neural implant.“Will you make a contract with me?”Guided by the cold logic of his most innocent creation and the limitless power of arcane forces, William must survive among arcane kingdoms, ancient beings, and buried secrets that defy reality.To succeed, he’ll need to master this new world’s magical laws, manipulate those who inhabit it, and uncover why he was brought here… and by whom.Vengeance forged his soul.Magic will shape his destiny.And the truth… will destroy the world.A story of magic, vengeance, and the birth of a new god of nightmares begins here...----------------------Warning:-------------------------------Explicit sex scenes starting from chapter 19, in any case this story is not focused on R18 it is just an explicit series.