I Became the Demon King After Going Undercover in the Demon Realm

Also known as: I Became Invincible After Entering the Demon Realm

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Othello is an arcane arts researcher at the Sage Tower.

One day, he accidentally falls into the Demon Realm, where he lives as a lowly undercover agent, waiting day and night for rescue from the human world.

Unfortunately, demons of every sort are always keeping an eye on him.

To escape with his life, he has no choice but to use human magic.

And then something terrifying happens.

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Othello: "First-level Fireball!"

The demons: "What is that? Fire can do that? How terrifying!"

Othello: "!?" The demons of the Demon Realm don't know how to use magic!?

The professor at the Demon Academy's eyes lit up. "A genius! You simply must come teach at our Demon Academy!"

Othello: "!!"

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Later on,

he punches a demon earl flat on the ground,

a marquis sees him and turns to flee,

and a duke comes to invite him to a tea party to discuss magic.

Othello realizes that he is invincible.

Even the students he teaches all become grand dukes.

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Several years later, the human world finally sends a rescue message, saying they are about to storm the Demon Realm and save him.

Othello replies, "Thanks, but... I've actually become the Demon King."

The human army: "??"

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Reading guide:

1. Lighthearted, Western fantasy style.

2. Invincible secret identity story.

Theme: In adversity, rely on yourself and never give up