Era of Castles: Starting with 99 Dragon Eggs - Chapter 406 - Sudden Change!

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.

Leiyin accidentally crossed into the One Piece World, and accidentally obtained the Naruto System.

What’s worse than finding out you’re that Louis XIV when you’re a baby?

Of course there is, for example, it’s still a magic version.

- Description from novelbuddy

A tale about the former leader of a special organization that served under royalty, now leaving his past life behind and unintentionally getting involved with the martial world.