Valkyrie's Shadow - Chapter 8Before the Storm: Act 10,

“Ryan was transported to a world of swords and magic, and he discovered that he was contracted with a system that made him stronger as long as he continued to practice basic magic!

When everyone else was learning all sorts of fancy magic, Ryan was keeping a low profile practicing foundational magic!

“Ding! Congratulations to master for completing foundational magic training 10 000 times. You obtained [Spell Casting Speed X10]!”

“Ding! Congratulations to master for completing foundational magic training 100 000 times. You obtained [Complete Fire Elemental Magic]!”

“Ding! Congratulations to master for completing one million times of blade-drawing. You obtained [Domain of the Laws of Magic, Saint Mage Rank]!”

Thus, after practicing foundational magic for billions of times, when Ryan unleashed his foundational magic, he realized that no one could rival him!”

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

After causing a tech disaster in the real world, genius shut-in Rin Katsuro is sentenced by the gods and banished to Ereborn—a realm ruled by chaos, where ancient scripts control magic and dungeons feed on trauma.He wakes up in the body of a legendary war criminal—the Demon King's General—and is mistaken for the adoptive father of a demon princess.Armed with unstable “Error Magic” that lets him rewrite reality like code, Rin doesn’t want to be a hero... but when angels declare war on the demon races, and his daughter calls him “Papa,” he might just rewrite fate itself.This is the story of a broken man with nothing left to live for—until an entire world starts calling him Dad, Demon, and Destiny.

The Venerable Xiang Yu, an eccentric villainous half-blood demon King was infamous in both the demon and human realm for being a cold-blooded ruthless devil that could kill with no remorse.Demons and humans feared him, cultivators wanted him as a trophy and the immortals saw him as a thorn in their side.The only reason he didn't get smote by the Heavenly King's searing lightning of divine wrath that could kill all mortals and immortals was because he kept the deadliest demons in check maintaining peace between the two realms.Despite his reputation, he had a small cult following in the human realm. They took him as their deity for his selfless acts of benevolence.Such rare selfless acts led him to rescue the fallen immortal Han Xin. But his benevolence became his downfall. Condemned to death, he faced an impossible choice: serve the Heavenly King or die with no marked grave.Xiang Yu: Hahaha... death isn't so bad after all.Heavenly King: You...Han Xin: Wife, you can't escape even in death. At least when you are alive you have a chance to run.Xiang Yu: QAQ...