Reborn in Demon Slayer: I'm Koyuki's Little Brother

Reborn in the world of Demon Slayer, he becomes Koyuki’s little brother. That’s right, she’s the woman who pulled the plug on Akaza’s internet. Absolutely terrifying.

From the start, he gets a Freedom System. As long as he does what he wants, he earns treasure chests.

“Opening a Golden Chest.”

“Congratulations! You’ve obtained the Mangekyo Sharingan and one Rize Kamishiro character summon card.”

“Boss Muzan, come out and enjoy some wisteria tea in the sun with me. Wouldn’t that be lovely?”

I’m no good at writing blurbs, so please check out the story itself. The protagonist isn’t a bleeding heart or a coward, and he’s basically invincible from the start.