Inside the Cave of Obscenity - Chapter Volume 5 3: Decisive Battle 1

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.

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

Zhou Rui had just turned 20 when his life took an unexpected turn. He was hit by a truck one day. Just as he was convinced he was about to die, something strange happened. Instead of waking up in the afterlife, he opened his eyes as a baby. Later, he learn he had reborn as Lumien Ofnir, the youngest son of a baron.As Lumien grew up, he realized this world was nothing like Earth. Magic was real, and creatures like goblins, orcs, dragons, titans, and other mythical creatures were part of everyday life.Fortunately, in this dangerous world, Lumien received another blessing. It was a system.Follow Lumien's journey as he begins to explore this new world with the support of a Harem System. The mysterious cheat that allows him to copy and develop the magical powers of any woman he has slept with.[Author’s Note: The earlier chapters might feel slow and boring, but I promise it’ll all be worth it once the pace picks up.]

To correct the mistakes of his past, a young man is forced to narrow the space between science and witchcraft, as he ventures on a quest to save his world from complete destruction.